Steamworks4j - just starting out on steam and have a few questions

Current status - I’ve written the games I want to sell but now need to integrate them into the steam environment. I’ve set up my company on steam, paid the money and am now waiting to be verified etc. I don’t have an AppId as yet.

Q1) I’m looking at using steamworks4j. Is this my best choice? I only need to find out whether the player has paid for the game or just testing it, store a status string for the user, store scores on the leaderboard and perhaps have achievements but this could come later. I’m really after the simplest interface available (I’m a bit stupid when it comes to other folks interfaces). Are there any easy to read examples available on the web?

Q2) is there anything I can do while I’m waiting? can I set up a store in advance? can I integrate with an existing test game and test the calls (I’ve heard Space Wars might allow this).

Q3) what are the calls? (did I mention I was a bit stupid)

Q4) is there a developer forum on Steam? I’ve searched but couldn’t find anything though this might be because I don’t have my AppId etc yet.

Q5) is there anything to watch out for when releasing java games via steam?

Q6) I have 4 games at present and wondered if there was a way to get the leaderboard info from each game to have an overall leader. I know I’m getting way ahead of myself but is this possible via steam?

Apologies for the totally random questions and thanks for reading.