The only pilots in the GOM who wear helmets are those flying government contracts,
AFAIK. The MMS requires the use of helmets on contract aircraft, but nobody wears them otherwise. GOM helicopter operations are slowly but surely headed in the direction of airline operations, in most areas, and the use of helmets is never going to be common. In 25 years, I've never seen anyone wear a helmet who wasn't required to do so by a government contract, and even then it was often avoided. I used to fill in on MMS contracts, and tried to wear the one helmet provided. It didn't fit, and I couldn't hear the radios properly while wearing it because of that, not to mention the discomfort, nor the safety issues with an ill-fitting helmet. Nobody I know of has ever had a helmet provided purely for personal use; they go with the aircraft, because of the expense. Maybe that has changed recently, but I haven't heard of it.
HUET training is hit or miss. There is no FAA requirement for it, and only a few major oil companies require it, for their employees and/or for aircrew on their contracts. Those companies are causing the training to be done for others, though, because pilots can be put on any contract at any time, and thus need to be qualified for many companies, especially majors. Some smaller oil companies follow along, and many service companies require training for their employees for the same reason helicopter companies do, because their employees will almost certainly be required, sooner or later, to work for the majors which require it.
Simulator training is not required by the FAA. It is used by a few operators, mostly because they are cheaper to operate than helicopters, and they are cool to show off to clients. Some oil companies are requiring real simulator training with FSI, both initial and recurrent, and I think that's a plus. That doesn't apply to most of the helicopter operators, though. The bottom-feeders aren't about to pay for any training, and that term applies to both oil and helicopter companies.
Inflatable vests are commonly worn by both pilots and passengers, although not technically needed most of the time. They are only required when more than 50 miles from a landing area, and it's not that often you're 50 miles from some platform. Still, most companies require their use all the time while offshore. Nobody provides breathing apparatuses,
AFAIK, but a (very) few pilots buy their own. They're rather bulky, and make getting in and out of cramped cockpits more difficult (is there any cockpit which isn't cramped, including the S92?). I'm not necessarily against them, just stating facts.
AFAIK 1000 is still the magic number for hours, at least for the majors, but I would not be at all surprised to see that change, because everyone is scrambling to find enough qualified pilots.