GlobalTim, I have heard people removing their masks in the middle of the night and having no recollection of it. It can be numerous things causing it. unfortunately I don't have a good answer for you. Are you new to treatment, perhaps you will get accustomed to the treatment and will stop removing it in time. Sounds like you are using a nasal mask, perhaps a full face mask would do the trick? something that is larger and a little more difficult to remove in the night? Are you using any tracking programs such as Myair or Sleepyhead? Perhaps your mask starts leaking in the night, subconsciously this bothers you and you remove it? You can track your leak and usage through these programs.
Good points from others. There are nasal pillow liners which may help with the zits. Not sure if is just the newness of wearing a mask rubbing up against your skin that is causing the pimples or perhaps the mask is not fitting properly and causing the issue. Keep your face and mask clean which will help. You may want to try a different style mask as wiredgeorge suggests if the issue doesn't resolve.
I would suggest you talk to your doctor to see what recommendations they have for you. Perhaps another treatment for the sleep apnea would help, such as the other's have suggested, an oral appliance? Perhaps a smaller mask (such as nasal pillow mask) might cause less claustrophobia?
Ruby makes some good points. Sleep position, medications, allergies or colds may affect your AHI numbers. The new mask may play a factor in it also, if the mask leaks are reading low but are increased from your previous mask, that may affect your numbers also.
What Ruby and wiredgeorge have recommended is great. I would also try to look online at mask, machines, so you can learn a little about them and get some ideas prior to going in. Perhaps check out some of the larger companies, ResMed, Respironics. When you go in for your sleep study with the CPAP ask them to try on some masks. Put them on, put some pressure on and lay down and move around. Unfortunately masks really are trial and error and sometimes it takes awhile to find something that works for you. Like the others said most insurances will not cover a lot of masks up front. So if you can't find something you like right off the bat, you may have to pay out of pocket or "deal" with the mask until the insurance will cover another mask down the road.
Ruby makes some good points, I would wonder also if you are having some type of allergic reaction to the soaps or the mask material itself. I would also suggest trying a different cleanser or mask liner. I have found that nasal pillows usually seem to be the best for stomach sleepers, since the mask is softer and less hard plastic digging into your face.
Were you using a nasal pillow mask prior to the machine change? A nasal pillow mask can be more drying to your airways than a nasal mask. Are you using heated humidity? That can really help. You mention your cpap pressure has changed, has the amount of air increased? That could possibly be some of the reason for the dry mouth.
Glad to hear the treatment is helping you.
You really only need to wear the machine when you are sleeping. If you are someone who tends to doze off when watching TV then I would put it on while watching TV. You are also fine though, if you want to wear it during that hour of TV watching also.
Whether you decide to proceed with treatment is your decision. Is the number of times an hour you are waking up (16) your AHI, or is that just the number of awakenings per hour? Usually an AHI greater than 5 warrants treatment. Today's technology makes the machines very quiet. If you are sleeping sounder you are less likely to arouse your wife from her sleep. Something made you get a sleep study in the first place, whether it was over concerns you had or concerns your doctor had. I think this is a nice article on why you should treat your sleep apnea http://www.alaskasleep.com/blog/reasons-to-get-your-sleep-apnea-treated-now