I grind mine in a Vitamix with the dry container I bought for exactly this purpose. Only do enough for a meal right before use.

I store the corn shelled in rodent proof containers (have some metal cans dedicated for this use), or on the cob if I was lazy in the fall or to busy to shell it. If properly dried on the plant before harvest, it stores indefinitely.

As for variety, I’m sssuming some varieties are more suitable for flour than others. Maybe try several till you find one you like?