This game looks really fun but I've never played a MOBA before. Can I get a quick rundown of how this plays?

As I've understood you farm attacking NPC creeps across several lanes for money/XP (while stopping the enemy from doing the same to your grunts), use that to buy upgrades until you're powerful enough to kill some NPC boss at the enemy base and win the match. Since teams are small and there's several lanes I assume there's a lot of splitting and playing solo and rotating between them to match enemy player numbers or get advantages?

I've played a lot of MMO (GW2) PvP so I'm comfortable with the idea of having to learn a ton of abilities that can be thrown at me, and I love buildcraft (though it seems you make a build on the fly mid-match in this), so this seems like it'd be up my alley.