Read the app listing in the play store. The size of the app is listed in the details, along with current version number, date of last update, etc.
As far as how much data is used, that is something you can look up in settings-->data usage
Agreed. It's pretty hard to figure out how much ram any app uses, short of installing it and looking at diagnostics. I usually don't care about that, though, with the way android manages it.The size or footprint of the app isn't related to memory(since I think this is a RAM reference). It's just the drive space. Not sure there is a way to see how much memory an app uses unless via logs. I mean you certainly can with logs but it's not something you'll generally see in app statistics...