well, being in Europe, things are a bit different. You can play the US servers, and many Europeans do b/c the Euro servers are not very populated (at least the English EU servers). I don't know much about them, but they are run by GoA, and not Mythic.
If you want to do play the US servers, which is all I know, then I would just go ahead with the free trial, and you can purchase the expansions online at your account billing informatioin if you decide you want (I believe it is $30 in game to buy the two extra expansions you don't get with Catacombs). If you want to play on the European servers, such as German speaking server, then I am not sure what is your best option. There may not be a 5th anniversary edition available over there.
As for getting to 50, well, for an experienced player with resources, you can get powerleveled in a matter of hours to 50. You can have friends do this, or you can pay people in game who do this as a living using platinum (the in game money). But to do it on your own, starting at nothing, I would guess it would take you a few weeks (2-3) to do b/c you are going to be trying things out and will not have great equipment. It used to be months, but it is much easier now. There is a new tutorial for new players (on US servers, I doubt it reached Euro servers b/c they are normally 2-3 patches behind US) that helps a lot. I have only ever played this game, so I am not great at comparing. Most agree this is the absolute best PvP game out there. Guild Wars has 8-mans I believe, and although this is three way realm war, where you can have large keep sieges involving hundreds of people, 8-man roaming groups are common. It is not instanced though, and you have to find other groups as your roam a large war map where there could be solos, duos, or even zergs (40+ roaming battlegroups).
Edited, May 14th 2008 12:52pm by thuri