HDPE tanks are the norm. They will work with 100% water to 100% methanol.

The pump can be slightly above the tank, but level or below is better. In some systems we mount the pump right on top of the tank. The pumps do not like to raw a long distance from the tank, the shorter the better(a few feet or less).

Foam poses some issues. Foam baffle meant for gasoline(hydrocarbon fuels) will be broken down by methanol. Foams specific for methanol usage will be broken down by water. We are currently working on a universal insert-able baffle for tanks and initial testing has proven it works well but a couple more functional issue need to be address before we put it up for public use.

Surge tanks work well of the proper return vent lines or large diameter feed lines are used between the main tank and surge tank.

Good luck.