Alright, so I just spent about an hour or so trading wins on the "Criminal Record" race (totalled about 40? 45?) with some patient soul and ended up getting those upgrades that were gated by WIN X AMOUNT OF TIMES and everything unlocks. Categories don't mean anything.
Some upgrades are gated by your player level, however.
@ghostytrickster: there's an option for a "closed crew session" but I'm not sure how that works -- I think maybe others have to do the same to get that lobby going? I just tried it on 360 and was put in a lobby by myself.
start your online mode from the pause menu in story mode and either use "solo session" or "invite only" if you don't want to deal with assholes. When you're done taking missions you don't have to worry about getting gunned down by some random as you're loading in.
so pause > online tab > play GTA online > solo session (or whatever you choose)
after you get an apartment and finally make enough to buy a more expensive place, you'll get reimbursed half of your original payment to put towards your new pad.
the only difference between the $400,000 apartment and the $200,000 one is the view. Same interior, same 10 car garage.
surviving a day with a bounty on your head rewards you with the sum of that bounty and some RP. hiding in your apartment counts towards that total time.
MOTORCYCLES: the Akuma has the highest acceleration, the Bati 801 has the highest top speed.
@demoskinos: You can quick restart missions after completing them by pressing RT at the leaderboard screen after you "like" it or whatever. So ideally you'd call up Gerald, get his Violent Ducts mission, kill dudes, deliver the coke, grab $9000 in like 3 minutes provided you have a crew that knows what's up, then restart. That's the quickest way to grind out money in the early game from what I've seen.
Lester has a mission called A Titan of a Job that pays $10000 as a reward but takes a bit longer, and Ron has one called Base Invaders that pays $25000, which is a bit more difficult than the previous mentioned.