Yes, GTA V supports multiple platforms.
Yes, GTA V supports multiple platforms.
Between PC and the other game versions, such as those on consoles, there are differences.
Any cross platform talks that include sony are basically not looking good any time soon, or maybe ever. It's possible that microsoft could do cross platform play between pc and xbox, but from what I can find it's not looking like that's happening soon either, but more likely than getting sony in on it