Yay! Trolls! They sometimes seem like the joke of the game cuz they're a little goofy. I think that flavor along with the Scottish thing is really awesome. We get together on thursday nights in Abington to play Warmachine/Hordes.
As far as what to play: You should pick a Warlock you like. The starter isn't OPTIMAL for Trollbloods, but it's great to learn to play and gives you a couple of utility warbeasts. Also, Madrak Ironhide, Thornwood Chieftan is the Warlock that comes in the box and he is awesome. So, if you're gonna start, the Starter Box plus a plastic Dire Troll kit is great! After that you could fill it out with some infantry. Fennblades are great in game and economical. You could get a Krielstone Bearer unit to make your infantry harder to kill. You could get a Janissa Stonetide who is an awesome utility solo.
Those are by no means what you have to buy, but it's a good place to start. I could talk all day about Trolls! I picked them as my main faction and I've been super happy with how they play and how they look.
Hordes is a fun game system. It is very much a risk management system (the fury mechanic) vs Warmachine which is an asset management (the focus mechanic). I like the risk vs reward decisions you have to make in Hordes. I play fast and loose.
I'd be happy to give you a demo on a thursday night. I've got a full Troll starter that I could show you. If you've got any more questions, drop me a PM. I'm not the best list builder if you're looking for competition but I have alot of fun with this faction.