I see so your not a natural mouth breather, sorry to hear about the hay fever, that must be a nightmare at times, and yes do try the humidifier it will ease that blocked nose, I have trouble with a deviated septum, it works for me.
Yes, finding the mask on the floor is a common problem we all have gone through at one time or another, it usually equates to the pressure being not set right, you will see a change once that is sorted, using your mask during the day is a good way of getting used to handling the pressure and the mask.
There is also something else you could ask your Doctor about, and that is changing from cpap to apap?
I mention this as I was on cpap for 18 months and had a very bad time with that, since October last year have gone onto apap which for me is much better as it delivers the pressure as I need it, maybe have a read up on apap first and see what you think.
Take note though, that if you ever did change over from cpap, then it will be like starting over again, and you may experience all those bad things you did when first on cpap, like I said look into it, and ask your doctor about it.
I hope that you get your problem sorted soon, good luck, and please let me know how it went for you.