1) read the directions on what the supplies you have require.
2) truck bed line on your floors? Sorry your car not mine but that is going to be a pain to clean dirt and hold moisture between the metal and the liner. Allowing rot to spread easy. I did that on a cab of a 72’ W200. Sand blasted spotless and allowed the Rhino lining process to do their thing. Professionals. With in 3 years the floors rotted out. Everything perfect to the t. I know off road guys swear by it and my truck was used every day.
3) I wish you luck with this process. I hope your car turns out better than my old power wagon did.