This has some good tips for a carpet install. They use windshield ribbon seal, but I had some butyl seal tape I bought at Camping World that I used for my 300. You have to ignore the first couple minutes of "comedy".
I don't ever glue carpet down, If the inside gets wet or you need to pull the carpet up for any other reason, you'll be glad you didn't glue it. I've ruined glued in carpet trying to pull it up.
Using a soldering iron for the seat belt holes works great!
[video=youtube;eHc5DaLD0Nk]https://www.youtube.com/watch?v=eHc5DaLD0Nk[/video]
BTW, there's a number of very good videos these guys have put out. It's all Mustang related, but the tech stuff applies to anything.