I did buy mine off Steam, but I think most of us did.
As far as seeing the servers is concerned, if you're using the in-game browser then you should be seeing pretty much every server there is. There's just no guarantee that there'll be anyone in them at various times of day. I'd check, but I'm out at Mt Isa atm and won't be back online in Brissie for another three weeks.
My suggestion would be to just keep trying. It tends to start slow, maybe only 8 people for about an hour or so, but after that there's a trickle of players coming in and before long it's filled to capacity. Certainly you can play on US servers and I have done many times (back in the mod days there was no other option). A higher ping will be a disadvantage, but it's far less of one than it would be in something more twitchy like CS or Quake. A local server will always be better in the long run though.