Hello Germ!
You and I started around the same time, though I'm coming to this as somewhat of an MMO veteran.
I'll address some of your concerns here.
As far as builds go, I advise that you build the way you like, initially. Try things out, have fun with it. If you find ways to make it work like a wookie in a woodshop, great! If it starts to cause you dissatisfaction,hit the skill trainer to reset your points. You can do so once per week for free.
My main is a 34 Guardian, and I seem to build mostly toward my main goal with a bit of monomania, and then go back and get the 'extra' talents later. The order you do it in really won't hurt you, in the long run.
As far as tanking/DPS goes, your best bet is to focus on what you do best, carve out a glorious path of destruction, OR shield your allies from harm. Go for broke, build in one direction, or carry some extra gear with you so you can change roles between battles. Inefficient? Well... Yes, actually. Your funds are often barely enough to cover all the training and gear and upgrades and OOH SHINY you run across; paying for two roles in one is just not helpful to your advancement.
Personally, I'm Vigilance, and when I'm running with my friend, I switch my focus for a shield, and pretend to tank in Soresu. Mostly, I jump in and chop things up, so they don't kill us. That's the extent of my 'tanking', to be blunt.
I seem to only have two AoE's available now, but they work just fine.
Did I miss anything? It's nearly 4am here... Tired...