Well, since you put it up for comment...
Every ship has:
Name - This is Star Wars. The name of your ship //matters//. Some might be Millennium Falcon, some might be the TIE Fighter TI-87Z. Each has a different impression based on the culture.
High Concept - 'Old Freighter Retrofit Continually'
One Aspect per Crew (PC or Droid) - This aspect is tied to the specific crew member, applies only when they are on board, and if they stop being crew, goes away. New crew add new aspect. Hire a cook? The 'Well Fed' aspect might be added. Who cares if a ship is Well Fed? Believe me I can think of situations I might invoke Well Fed to get something cool.
Systems (ship skills) - and the PC skills that affect their efficiency:
Hull (Mechanics)
Weapons (Mechanics, Shoot)
Engines (Mechanics, Pilot)
Shields (Slicing, Mechanics)
Sensors (Slicing, Pilot)
Comm Relay (Slicing)
A skill line/tree/pyramid is as good a way for representing ship functions as any, really, so I think that should work just fine. You may, however, find that you need to modify how you represent them if the way players/characters interact with the ships changes. (More on that in a moment.)
Hull, Shields and Sensors will all have stress tracks. (Why sensors? A slicer can use the relay to put out crazy stuff to jam your signal) Damage done does shields until its gone, then hull, and once its gone, everyone better get their ass to an escape pod. Once Sensor Stress is gone, hit the FTL and get the hell out of there in a random direction.
Point of curiosity: What's the thought behind a sensor stress track? From your basic write up it looks like you're looking to represent things like jamming progress with it (with, presumably, consequences inflicted being something along the lines of 'sensors jammed', 'no communications' and similar?). It may be helpful to consider how. such damage is counteracted. With shields and hull damage the answer is generally 'reroute power / perform repair actions' to both remove stress and initiate consequence recovery. For counter jamming kind of things, that might possibly be less immediate than you want, especially if using standard consequence rules.
I might suggest looking at representing this kind of thing with aspects created via the create an advantage action since this would allow ships with counter jamming personnel and equipment to remove the negative 'status effects' in a manner that doesn't require consequence recovery. Additionally, as a lore matter if I'm remembering my Star Wars fu correctly by this point in 'history' navicomps and astromechs are the primary way of calculating hyperspace jumps in most places as opposed to the much older hyperspace beacon networks and that misjumps are generally a result of either not doing the calculations (jumping too quickly) or sustaining physical damage to those components.
Anyway, something to consider. The way you've got it should work just fine in my opinion, just wanted to present some options.
Ships get 2 refresh per refresh used to buy the ship: refresh can buy stunts or extras.
The 'system pyramid' is capped at +1 the refresh cost of the ship.
A common basic frighter might have for 1 point, might have:
+2 Engines
+1 Hull, Relay
An effective, 2 cost cool ship might have:
+3 Weapons
+2 Shields, Engines
+1 Hull, Sensors, Relay
It might be more crunch than you want but you might also consider capping the amount of refresh / the skill pyramid by its class or size or something similar. A given hull will only take so much tweaking and modification before there's just no more room / the engines aren't powerful enough / you've essentially rebuilt the whole thing into something else. Could be that's actually too 'simulation-y', since the point of going with Fate is generally to reduce crunch, but again, it's a thought.
Big glaring hole: Exactly how 'PC skills affect ship systems in their efficiency'. I haven't even really gotten to that stage of deciding yet. I have this vague idea that the player rolls the appropriate skill and it adds a bonus like, Shifts (success over difficulty) / 2, to ship skill. But that's so off the cuff, whoa.
This would be the big one to consider. How your characters interact with the ship will determine in large part what you need to represent on the ship mechanically. Off the top of my head I have a couple of suggestions. The simplest one that comes to mind is to use a ship's skills as a 'cap' on the relevant player skills. So you have an X-Wing pilot, for example, with a piloting skill of +4. That's great in his X-Wing which has an engines rating of +4, but stick him in a freighter with engines of +2 and he's not going to be able to use his skill to it's full potential. He's limited by the quality of the equipment he has. Conversely a farm boy whose only flight experience is in T-16's may have a piloting skill of +3. He can use all of that skill when he gets his shot at glory flying an X-Wing but he can't use the ship to it's full potential because he's just not quite that good.
Though, you know, your mileage with farm boys turned rebel pilots may vary.
If you really want a crewman to be able to improve the ship's performance, you might allow crewmen using a system at which their relevant skill is better than the ship's rating to either create advantages related to pushing the performance or to gain a +1 synergy bonus (similar to the 'teamwork' bonus given in some combined rolls). So in this case, a rebel pilot flying an X-Wing with engines at +4 and a piloting skill at +4 is using it to it's maximum potential. A pilot flying at +5 can push his system's performance because he's just that good, and gain a +1 synergy bonus to the roll, effectively letting him use his whole skill. A mythical pilot flying at +6 (if such a thing exists) is still only rolling at +5. He's got the same ability to push his ship to the limits, but in this case his ships' limits are holding him back. There's only so much the tech can do for him, despite his incredibly high level of skill.
You might consider also using a 'traits' system (ala Transhumanity's Fate) to append and clarify the ship's basic aspect. If you don't have access to that book or haven't read it, Traits are 'sub-aspects' that are attached to a given aspect and are invoked and compelled via that aspect, but serve as justification for doing things related to that trait. So you might give our example X-Wing a High Concept 'Red Squadron X-Wing' with the traits 'Starfighter', 'Maneuverable' and 'Hyperdrive'. Those traits all 'live on' the High Concept aspect and serve to justify things like flying through Beggars Canyon (because 'Starfighter' tells me it's small and 'Maneuverable' says it should be able to do this) whilst 'Hyperdrive' serves as justification for long range travel but can //also// be compelled (via the parent aspect) for it to break down or get damaged and strand the pilot. Again, this might be more crunch than you're looking for, but it's a suggestion.
Finally you'll need to decide how and when characters can make ships do things. I'm a big fan of Aether Sea's 'stations' mechanic for this. A ship has so many stations and those stations do specific things. A piloting station lets a crewman make piloting rolls and move the ship. A weapons station lets a crewman make attacks and so on and so forth. I am personally a fan of this because, one, it allows for another level of differentiation between ships and two it allows you to express certain concepts mechanically provided you have enough people. (Also I suppose, three, it gives players clear indications of how to use all those shiny stats the ship has).
So for example we have a highly modified YT-1300 freighter with big engines and some guns. It has 2 pilot stations, two gun stations, an electronic warfare station and perhaps one or two others. So in a given round of conflict it can move twice (or make two piloting rolls), shoot twice and jam someone's comms but only if it has at least five crew. If's being piloted by only one person... well it can move once. It's a big ship and even in the cockpit leaning over to flick that navicomp switch by the copilot's chair is a pain.
Anyway, slightly ramble-y there. Looks like you've got a solid foundation and some good ideas about how to proceed. Hope this wall of text was helpful in some way, if only to get you thinking 'no really, I don't like those ideas and these are the reasons'.