So i got a a bunch of seeds from a great plant gone hermie. i've heard they will all be female, is this too good to be true?
Nope, a hermie female can only make gametes with XX chromosomes so it's true! There's no possibility of a XY combination!

is ths why i've had females with any bagseed and half males when getting them from a seedbank?
Yup- commercial growers don't typically keep males around so any stray pollen is more than likely from a hermie female.

if they are feminized, i wonder if they will be more likely hermie too?
Yes. They will produce male sex parts under similar conditions to the mother. So if the commercial grower ran hot and got hermies, if you run hot you can expect them too.