Re: fuel tank
I would really take a good look at what the inside of the tank looks like before you fill it up with almost 800 lbs of fuel. It will be much easier to take out and clean if needed now.
If it looks clean before you put 10 gallons in it and stabilizer, I wouldn't worry about it. anything you top off will dilute the water and your separator should take care of it.
Now if you have 20 gallons in the tank, 10 gas and 10 water, that's another story!