Glovebox mount is the most stealthy, most decent head units come with a remote control. There is a couple under dash mounts as well.
I agree on the need for an amp. I'd stick with a decent digital amp for the footprint. Nice and small.
alpine decks are pretty good, and I didn't have to replace many due to failure that wasn't customer induced. I Personally liked kenwood, but things may have changed since they are owned by JVC now.
The best advice I can give is to know your installer, not salesman, salesman are based on spiffs and what they like, or the company is pushing. Installers generally know their own abilities and what fails... Or doesn't.