Hello all! I will assure all of you what you are experiencing is 100% normal. I currently am a RPSGT (Registered Sleep Tech) with 7 years of experience. Currently I am a Clinical Director at a local Durable Medical Equipment company. In regards to the dryness ask yourself did you ever have dryness before using PAP therapy? Also, keep in mind when using a full face mask and breathing through your mouth, dryness is almost to be expected. Just picture a fan more or less blowing into your mouth all night.
Ayr is a saline gel that is safe to use with PAP equipment. Ayr is a great suggestion! Biotene is also a suggestion but I saw someone has tried it to no avail. Increasing your humidity will help, just watch out for rainout or excess moisture in your tubing. And lastly as silly as it sounds keep a glass of water near your bed and also be sure to keep yourself hydrated during the day.
Hope this helps!!!