Yes, yes, YES to the dive-tool. It doesn't have to be a samurai sword, but there's a knife out there that's compatible with where you dive and the potential hazards unique to your location. I've been entangled twice in discarded fishing-line - once on a Northeast wreck and once on a dopey reef dive. My buddy freed me the first time with his little knife, and the second time, I just moved very slowly and deliberately to free myself. But I knew that my buddy, as well as I, had the cutting tools at hand if my slow contortionist act failed to work, so it was easy to remain calm. In other cases, too, a knife can be handy...I've used my little knife to dig into sandy patches and help deal with unexpected currents, for example. That said, there are locales that forbid divers from carrying knives, so be sure to check with the author-itehs before you splash.
Dramamine is my FRIEND. Take one or two the night before, and one the morning of your dive, and you will be golden. $2 insurance from a crappy day. I'm not a fan of hurling into my regulator. (And frankly, having seen the way yellow-tailed salmon swarm to vomit-clouds, I gag every time I hear someone order it in a restaurant.)
As for bubbles hitting your mask...never been an issue for me, as I have a reg with an exceptionally wide exhaust valve. It directs the bubbles pretty far from my face. (But that's my reg's only selling point, so I'm not going to recommend it to you!)