The pre-expansion game is capped at level 50 while the expansion raises it to level 60. The expansion is solely for gameplay beyond level 50 and also requires you to have completed the Main Story Quests from the original game and all patches up until expansion. The Main Story Quest is also in a way a tutorial to the more advanced aspects of the game so doing that while learning the about the Duty Finder and such helps! Also don't be afraid of testing new classes and get used to cross-classing!

The problems with communicating for trialing seems pretty harsh. I had friends testing the game that got tired of not being able to talk to each other. I'm not sure how to solve this, maybe if there is a linkshell for new people on your server... I don't know. although if you have any specific questions, fire away here and I can see if I can answer anything.