Rambling on is not a problem. Better that than nothing to work with.
The Dreamwear gear seems to be the most adaptable option at the moment but I have no experience with it personally.
Much of the information you seek is already in various threads of this forum if you have the patience to browse but I'm confident that there will be more specific responses here shortly.
Greetings, First of all, relax. It was a shock when I was diagnosed (healthy, endurance cyclist, female) but my heart was acting up and my concentration was gone. I was happy to learn it was apnea and not a failing heart. And happy to find this forum where most are positive about their therapy. At that point, my only experience with CPAP was sharing a hotel room with a travel buddy 25 years ago. Was that machine ever annoying-so loud, wished I had ear plugs. A pleasant surprise that now the machines are so improved, and quiet. As for a mask, I was able to try on several at the sleep clinic, and chose a nasal pillow. I do flip side to side and have no problems with my set up. Hubby was very concerned about noise, but it is not a problem, even when spending a couple weeks in a VW Eurovan.
So first of all your apnea with an AHI diagnosis of 18 is at the lower end of the moderate range for apnea. Many of us are much higher, my wife at 80+, and myself at 37. While there is not a direct relationship, generally a lower AHI will need a lower pressure and will be easier to correct. That assumes there are no central apneas of significance. Central apnea can be more difficult.
Choosing a mask can be difficult, and a full face generally is more difficult than a nasal, or nasal pillow. The down side of the nasal type is that if you open your mouth in the night, it will show up as a large leak, and will most likely cause a sore/dry throat. Treatment can be compromised too. Most if they have that issue are directed toward a full face mask as a solution. The other alternative which both myself and my wife use is mouth taping. It is not nearly so bad as it sounds.
There are probably hundreds of different masks. I use the ResMed AirFit P10 nasal pillow, and like it except for the flimsy straps. I switch positions from left side to right side to back several times a night, and it works. My wife uses a F&P Brevida nasal pillow and gets good results. The new Respironics DreamWear mask system looks interesting. The same headgear will accept a nasal pillow, nasal, and minimum contact full face insert. It would minimize the cost of switching types if one does not work out. The nasal and nasal pillow are very similar with one on the nose and the other into the nose some. Just a guess but I would expect the nasal pillow one to be a little more stable. I have no experience with any of them.
Your ResMed AirSense 10 is a good machine if it is the AutoSet model. Who will be setting it up for you? The Doctor? I think the most important thing to use in the setup for maximum comfort is the Auto Ramp feature, and a high enough Ramp Start pressure. About 7 cm should be comfortable. By default the machine will start at 4 cm which can feel suffocating. I also like to use the EPR feature set at 3 cm and for Ramp Only mode. This makes it more comfortable to go to sleep but does reduce therapy effectiveness after you go to sleep. You may have seen the link before but just in case here is a link to the technical manual for the AirSense 10 machines. Even if your doctor is going to do the setup the manual is a good read so you understand how it works and what it is capable of doing.
As far as tips on getting started, I would make sure to use the machine for at least an hour or so while watching TV or reading a book, before you actually try to sleep with it. You do have to make friends with your mask and machine so you are comfortable using it when sleeping...
Finding what works best can sometimes be easy or sometimes a very long ordeal. I started out with a nasal pillow then went to a nose cover then a full facemask. That works best for me because my mouth would open during the night which was not good and caused a very loud noise. I have had trouble finding anything that didn't leak until I started using a full mask lined with memory foam. I do know that there are places that sell liners for various types of masks that help with leaks. I have not tried any of them. This is a good forum for asking questions and making comments. Glad you found us.