I am not @menta, but we are friends and I too live in Siem Reap. I think you were being straight forward so I will address your issues from my own personal experience...

1. never had that problem.
2. Khmer weddings are a blast. If you have ever been you will know what I'm talking about. yeah when music goes for 3 days, you don't know the family but you hear them going early to late, yeah it can suck. but ever lived with a shitty roommate, had THAT neighbor, or just been that guy having a weekend gathering, you just learn to deal with it. I would rather miss out on sleep for a few than worried about getting shot in a movie as you do in America. I know this has become and international platform, but so many americans have so little understanding of Cambodia.... so there's that...
3. You ever hear that anything too good to be true probably is? Live by it? Same same, besides, I'm not a sex tourist so never been a problem and have had fun at bars with some ladyboys. they are just people trying to eat for the most part.
4. True, underwear can be a bitch, especially for the ladies. Most women i know order online or if they live here and have a visitor coming, they ask for a few bras and panties. No big deal really.
5. As far as your whole Sharia law thing, i call bullshit. There is a really great diversity here and the Muslims, Buddhists, Christians, Atheists, Animists, etc. get along just fine. Yeah their healthcare system needs improvement, no doubt, but again you bring up the sex thing. You can get laid without paying for it. There is tinder, bars full of drunk horny women, and if you have a fantasy girl in mind and that is YOUR thing, if you go to the right place, and thru the right channels, you can find that without it being a chick with a dick, so relax. There are clinics here, if a major incident occurs, you may have to go to Bangkok, but being a poor American, i haven't had health insurance since I was 18, so i'm used to that being a problem.

Not trying to sound rude, but just being honest from my experience. For the most part, this is a thriving, growing, community of all kinds and filled with possibility. As far as the expat thing, several friends have social enterprises, there are coworking spaces already and a growing young Cambodia population eager to learn, very industrious, and hoping for a bright future, and integrating with the locals, collaboration, cross-pollination of this kind may just be what is direly needed....

Just food for thought. Love and respect.