Heat Sinks first, unless you’re going for Galaxy Exploration, in which case Engines. It can be worth looking for the rare ones.
Don’t bother with reactors until you literally can’t afford the power cost of your next bit of equipment.
Ships can fit in wherever - that’s personal preference as to how much you prioritize them. I’d actually also recommend considering certain weapons like Vulcan Chaingun and Ion Blaster that are extra-effective for specific mission types (like Comet Chase and Supernova respectively).
After you’ve got your “Dream Ship” I’d focus on Extra Slots (and a Laser Pointer, depending on your weapon of choice). Satellites can usually wait until much later because they’re easy to find in-mission anyway and you won’t be using them all the time regardless.
Pick it up in a mission or two and see how you feel about it. Some people (me) love it, others think it’s atrocious. It’s a very different play experience.