1. For the dry mouth, you could try an OTC product for dry mouth. They make mouthwashes, toothpaste, etc. My dentist suggested that for me since I suffer from dry mouth as well.
I see you're using a nasal mask. The first thing that comes to mind is you're opening your mouth. Have you looked into that? If you are, you need to either get a chin strap to see if that helps or get a full-face or hybrid-type mask so your mouth will be covered. If air is leaking out of your mouth then not only will that cause dry mouth but you're not getting the proper xpap therapy.
2. Can't really help with the dreams.
3, I see you use a nasal spray for allergies. Do you use that at night right before bed? If not, there are OTC saline sprays and gels you could use right before before bed that might help with the dry/sore nose (I'm assuming you're talking about INSIDE your nose not outside since you're using a nasal mask not pillows.)
4. Leaking noise (and the feel of it on your face!) can be frustrating. Your new mask will probably help with that. And FOR ME, having a new mask every two months helps. I do clean mine, obviously, but after a while even that doesn't work as well as a new mask for the best seal.
And yes, keep reminding yourself of the positives!! You'll get through this rough patch!!
I'm sorry you are having a rough time right now with your CPAP therapy. As far as dry mouth goes, there is a thread on this board called: New product for dry mouth.
You say you are using the humidifier, how high are you using it? Too much can be just as bad as too little..
Hopefully, when you get your new mask, things will get better for you.
Best of luck to you and just keep on trying, I know things are frustrating for you right now but just stick with it and keep us posted as you go along.
Hang in there for more suggestions.