You don't HAVE to, but it's a bit pointless not to.
If you have it on PS3/XBOX then you don't have to install it. Place it in the drive and run it.
there is no option to play two player on GTA 5.
You will have to be on a certain mission to play the cop mod on GTA. GTA is a type of game.
You will need a PlayStation Plus membership if you wish to play the online multiplayer on your PS4. The same goes for Xbox One, where you are required to have Xbox Live membership if you want to play GTA
Yes you can
problably not my pc laggs on every thing but not gta 5 san andrea or vice city
No, but loads of other people do
Yes it's ok.
gta5
Yes. Some of them will be there just like that guy from GTA 3 was in GTA:SA...
Yes
There isn't there any 2 player mode in the gta vc game.You can play multi player in the latest game by Developer that is GTA 5.
Yes of course. You'd simply have to play it over a wired connection.