So, keeping it simple.

I'm looking to get into Doom multiplayer. I played it... a couple of times about a year ago, it was great fun. REALLY fun.

1. Should I use Skulltag or Zdaemon?
2. Do I need to buy one (or more) of the Doom games off of Steam for the necessary files? If so, which one(s)?
3. Is the multiplayer relatively active at all these days? Or did I completely miss the boat? :(

Thanks in advance.