Formula 3 & Evinrude fr 31-m

[Tokate]

Hey,

I just bought an old formula 3 boat and evinrude fr 31-m. I'm quite lost with the engine and I have many questions.

The package i bought includes two powerheads, two lower units, propellers and lots of different parts. I have two almost similar rigs. There is couple differences and one is that the exhaust pipe is on the other side. Is that from the older fr-19s? (Look second photo down right corner)

I have understood that I need to use avgas and oil ratio is something between 4-6%?
I'm not going to race with the boat so I don't need to take everything out of the engine so what rpm would be good if I dont want to change pistons after every run. I read 8500-9000rpm is okey?

I know the engine need to warm up when the boat is on a trailer. But why some people use some kind of plate instead propeller while warming up the engine? Why can't I warm up the engine without a propeller or with the propeller?

Does anyone have a parts catalogue for the fr 31-m?

I would like to get any tips and information related to fr 31-m!
And sorry for my bad english.