I didn't have to, and I think it might depend on if dash speakers are in the way or any other items. For me, I did not have to do anything as far as removing things or disassembling the dash.
Yep - from the factory you may have a nut up inside plastered with sealant, loctite AND a nylock nut. I did.
I ended up drilling them out. MUCH easier that trying to remove them. Then I replaced them with appropriate grade hardware bolts etc.