Verizon wireless - could i switch to the iphone?

I currentley have the LG ally & ive had it for about 10 months. 3 buttons are broke on it - the call button, the home button, and the camera button. Also, every day it says my memory is full when i dont have any apps on it. I have about 10 songs, & 25 pictures. It's ridiculous! & Its soo annoying! I searched the memory thing up and a lot of people with this phone have it and they all hate it. Anyway, I'm going to the verizon store sometime this weekend and i was wondering if there was any way I could get the 32G iPhone without getting a new contract. If i could, around how much would it cost? & if i were to get a new contract, would that mean my phone number changes too? thanks xx :)