The major piece of advice I will give is, with an older schoolbus, it is definitely worth your while to take out the subfloor and rebuild. There was a lot of rot under the rubber flooring, so taking it down to the metal, while it was a pain at times, was definitely the wiser choice.

When we bought the plywood for the subfloor, we didn't have anything big enough to haul full sheets, so I had the sheets cut in half (4 x 4). This was also a timesaver, as the bus width was right at 7 1/2 feet, and we were able to lay the half sheets down one side and then cut the other side to fit. Fewer cuts, less hassle with obstacles, and easier to handle all around.

I did a couple videos before I was on steemit, I may put in some tutorials eventually.