I've had a CPAP machine for a couple of years now. It does take awhile to get used to -- don't be too hard on yourself if you sometimes throw the mask off in the night. I had to change the type of mask once, but now I'm settled into a pattern.
Taking something to help you fall asleep is a good idea. The MDs are usually stingy with sleeping pills, because they don't want you to become dependent, but you can use Tylenol PM, or similar OTCs, which just have some benadryl.
Our bedroom is so cool, all year long, that I could not stand using the humidifier feature -- I always got water in my nose, even if I had the humidity very low and had the tube well covered with fabric. So, I gave up the humidity thing altogether.
Keep trying! You will feel better for having better quality sleep.