I would say the larger snake is female and the smaller is male. The only one I question is the smaller one as a better under tail photo is needed. I can't really say which species they are from your photos.
You are correct about the toads. I would also caution you about feeding mice(fur bearing) Pinkies are safer in my opinion as they don't have fur which can cause impaction.
Here is a link to the care sheet which will give you much information. Why not feed some night crawlers?
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Garter Snake Forum - Garter Caresheet