I agree with Marie on the food thing. It is always better to go wet, especially for an older girl like yours
Did you change your routine recently to make her start pawing at the door? I'm assuming she hasn't been doing this for 12-14 years lol. Honestly the best thing you can do is ignore her. Don't come to her, don't talk to her, this will tell her that hey she is getting somewhere and she naturally will persist (kitties are so smart!). Something that might help you is to play with her before you go to bed. By wearing her out perhaps she will sleep in a little.
I would go with what Marie said about leaving wet food out. It's not something I've ever had experience with, since when the wet food comes in my house it is always inhaled in 3 seconds lol.
Welcome to the forums, and I can't wait to hear more about your kitty and to see pictures. What's her name?
1) & 3) Wet canned food is better for her than dry kibble. Is there a reason you want her to eat the dry? If you're concerned about the canned spoiling, you could freeze part of it, and then it will defrost through the day.
2) I take it this is a new behavior on her part? There are a couple of things you can do if you don't want her sleeping with you. Put her in another room with her food/water/litterbox before you go to bed.