Will leave the electrical questions for others as it has not been a concern for me.
2007's can only be had if you can find one on a lot somewhere. MI Truck began building the 2008's a couple weeks ago. Orders have been taken on 2008's since April. I ordered an '08 Limited on June 7th and have been given a build date of 7/16, which probably puts it on the dealer's lot around the first of August. Figure 8 weeks from the order date and you will be in the ball park . . .