You'll have to pay full price, since you buy each apartments separately and it's not an upgrade from one tier to another.
The plan is that when you come up to something, if you think you should be able to interact with it, it's likely going to be interactive (but not everything). As for weather, there won't be anything special. There will be rain that's for sure, but no random events caused by weather.
N/A
Of course you'll be able to customize your vehicles. The type of vehicles and tires installed will affect the performance on various environments.
Car wash is one of the things that'll be added later on after the full release.
Will have to ask for that one. There's really not much info about the map. But the one in the police department is outdated.
Houses are unique and has to be purchased with in-game money. I know you haven't asked, but pledge apartments are special and can only be obtained from the website. There will be similar layouts in the game that you can buy with in-game money though.