First thing I would say is, don't worry about making everyone else happy, you'll be doing well if you make *some* people happy!

Smartalec-ness out the way, my answer to your first question would be how much will the players (including GM) need to play in "your" universe?  If you tell people "you see an X-WIng chasing a TIE fighter" that is enough for them to picture the scene and interact appropriately; if you say "you see a Crusader chasing a Phantom" is that a pair of Battlemechs, two US Navy jets or a British tank from WW2 following a ghost?

Some people will be happy with the absolute minimum necessary for them to picture the scene and they will fill in all the "tiny" details themselves, others will want to have the smallest detail spelled out for them so they can figure out a real MacGuyver-style lash-it-all-together-and-win session, still others will want enough detail to be in the middle of those two extremes.

For example..:

"You're standing in front of a jet engine"

"You're standing in front of a Rolls-Royce Pegasus 104 with the fully digital engine control module fitted in the upper position and the uprated igniter package, recently removed from a Return-For-Parts 29 Squadron Harrier GR9A"

"You're standing in front of the engine from a scrapped RAF Harrier"

To an extent, the amount of detail you need to provide is dependent upon how well the players will know the base material - if it's well-known like Star Wars then you won't need as much detail as you would if it's less well-known like Traveller: The New Era (most of us have at least heard of TNE even if we don't know much about it, but to the people who think Star Wars invented SF* you would need to explain the 3I and everything through the basics of MT and Hard Times as well as specific details about the Reformation Coalition etc)...

*yes, I have worked with people who really thought War of The Worlds was written for the Tom Cruise film and that Will Smith invented Azimov's Three Laws Robotics...