If it's as loud as I'm imagining a helicopter landing next to the exam room is, that would definitely get the proctor to stop the exam and ask about what's going on. Not exactly a one-to-one comparison, but it started thunderstorming during my LSAT and I looked outside when there was a huge crack of thunder. The proctor instantly stopped the exam and made me show him my surroundings and explain what had happened. You should probably find another room to take the exam.

It took me about 2 months of casual studying (maybe 10 hours a week, max) to get logic games under 9 minutes/game. I also started with zero knowledge of formal logic and basically worked through the LG section of the Kaplan Prep book. Given your prior experience with formal logic, I'd expect you'd be able to master logic games much faster than I did. Like other people have said, get very comfortable with the rules and becoming proficient in conditional logic and work through some games without a time limit, repeating the games every few days so you begin to make inferences quicker.

@ They're not going to allow you to plug in any type of external hardware into your computer while taking the test. It doesn't matter if your audio quality is bad. The only reason they need to hear you is to ensure you're not receiving instructions or cheating in any way.