Ok I completely missed that despite reading it. Clearly not enough coffee. As for mail in, you only have to mail in custom configs usually. If you get an off the shelf one they do it in store. I've done a couple before. One took an hour.

Batteries - well they need to be stuck to something so they don't bend. Apple's design flaw is sticking it to the top case which is the problem.

Well it was a $2500 MBP and it paid itself off because I made more cash than that in 3 days with it (unfucking an iOS app for someone).