1) You have a "My Account" tab at bigfishgames.com. It has your entire purchase history so you can redownload and reactivate any game you have purchased at any time, as many times as you need to.
You are buying a lifetime license for the game. That license covers you, anyone in your immediate household and any PC or Mac in your household.
You can redownload and reactivate the game as many times as you like and install it on as many machines as you want as long as you adhere to the "household" paragraph above.
2) Two issues here:
Game Club - Game Club is $6.99 per month for a bunch of benefits and includes one "Game Club Credit" that can be redeemed for any game. You can always buy additional games for $6.99 whether you are a member or not.
Novemberfest - This is a promotion where if you buy 6 games in November you get a bonus Game Club Credit for a free game. If you buy 3 additional games, you get a second Credit for another free game. The term "Buy" applies to any coupon, any price point, any game on our site.
3) The club does not affect your ownership, it affects your ability to access the other benefits (see site for list of benefits). Once you buy a game, it is yours for life.
4) Chances are BFG will get it.

There are only really two developers out of over 600 that we work with whose games we do not offer.
Hope that helps.