Omaha is easy actually. Just run up to the closest obstacle, and duck and wait for them to stop firing (you won't get hit if you're behind it). While they stop, run up to the nearest one, duck, wait for them to stop firing, repeat. And if you need to you can get healed by the medic.
Now the Sniper Town, that is a bunch of crap 🙂. Had to cheat through that one. I'm stuck on the train station one right now. I've tried a few times but I keep getting hit by all those MGs in the towers. I'll get it though, it doesn't seem that hard, just gotta play it a little more.
And I finally started using Quick Saves/Loads right now. Before today, I have never used them heh. I never even knew there was them.