1) This is a Census of all server populations as of the end of October. I am not certain how the economy is affected on different servers, although I know prices to be higher on legacy servers. The dutyfinder will contact and create groups from players across all servers, and if you fiddle with the settings, will even cross in to the japanese and euro zones for you.
2) The game does become very group-focused starting from lvl15. I would recommend you look on your server for a lowbie-friendly FC. You can check the forums to see if there is anyone offering that, or you can shout in one of the major cities and hope someone notices you. In regard to ilvl, that is only relevant for endgame content only. Each item has a level assigned to it, from 1 to 90. You will need an ilvl of 80+ for endgame raid content. The fact you do not know this means the other player assumes you're just an ignorant lvl50, or is only exclusively recruiting well-geared lvl50 players. If you tell them you're a lowbie, but experienced in other MMOs, they may be willing to accept you.
On the other hand, you might ask to join a linkshell (LS). Those are closer to social groups and they might be more friendly than FCs to help you level up. Again, check the forums for any advertisements for friendly FCs or LSs. If you can't find any, I might recommend joining Leviathan server. We've set up a couple friendly LSs for lowbies to network and group.
In all seriousness though, dutyfinder presents a big problem, especially for dps classes. They're trying to fix that in patch 2.1, and it will help, but I'm not sure how big of a help it will be. For most DPS at end-game, the average wait time is 30 minutes. For lowbie dungeons, the wait time is much much longer. You will want to find a party with a tank or healer class to speed you along. Finding a FC or LS interested in lowbies will help you find members before queuing.
3) I would doublecheck the specifics on your antivirus, firewall, and power settings and compare them to make sure they're exactly identical. Otherwise, I have no idea what might be causing the problem.