are there any significant differences between PS3 and ps4 game play in terms of mechanics or skips?
About how much time would be lost to loads?
Would it be worth learning on ps3 to begin with?
Is Xbox the same or similar enough situation?

thanks

PS3 and Xbox are awful ports.

In short, TEW originally was only gonna come out on PS3/XBOX but decided to bring it for next gen as well so they put less time into optimizing the PS3/XBOX ports. The loads are way worse.

PS4 or PC is what you want.