Definitely wasn't a starter weapon. Sounds like you got a decent upgrade to start off with. There's currently no push-to-talk or option to disable voice chat in game, so that can be a bit frustrating. I think I was two matches in before I realized I was transmitting everything. Unfortunately, CTDs are fairly common. A lot more common than in single player at any rate. You just have to hop back in and try again.
The Demon Commander boss is really difficult until you figure out his move set. There's a thread either in this forum, or over in the Combat Strategy forum that has a video showing what to look for to dodge that attack where he pops out of the ground spinning. I'd recommend taking a look at that. Generally you just want to stay spread out and keep moving during that fight. Keep an eye on the Commander and start sprinting (tap shift) when you see him go underground and continue to do so until you see him again, or 5-10 seconds has passed.
The Templar Commander is the other difficult boss. He's actually really easy once you're familiar with him, but he wrecks inexperienced groups. The first thing you need to know is that you should never try to tank him. He's very, very slow, so you can just kite him around while team mates whittle him down. He has three attacks you need to watch out for:
-The first is his "cyclone" style attack where he just spins in circles with his sword, getting progressively faster as time goes on. He'll pause and hold his sword off to the side as if winding up for the spin, that's your indicator he's about to start. When you see it, make sure you're out of melee range. If he's targeting you, try to put an object between you. Wall, railing, crate, whatever. He can't jump, so he ends up just spinning in place harmlessly. If you can't do that, then just keep running until he stops.
-The second attack is one where he slams his sword on the ground and sends out a shockwave in the direction he hit. He does this three times in a row, so make sure you dodge all of them. Again, this one's pretty easy to dodge. I believe he holds the sword over his head before using it, so just look out for that. When you see it, start running from side to side. That way when he strikes the ground, you've already moved out of his path. Just try to make sure you aren't aiming him in the direction of your team mates.
-The final attack you need to watch out for is his leap. He'll point at someone and then the ground will be marked with a cloudy red circle. Again, you just need to run out of it quickly.
As for the Venatori Commander... well, she's a pushover. I'm almost more concerned about the Venatori Stalkers than I am the Commander. She's got some attacks of her own, but none of them are particularly dangerous, so just burn her down as fast as you can.
Anyway, it can be pretty frustrating at times, but it's also a lot of fun.