How terrific for you! If you want to sell them, then you do want to have a general idea of value. Online htere is a http://www.comicspriceguide.com There is a small subscription fee. If you don’t want to pay it, check the library. They may have advice or perhaps a copy of Overstreet Comic Book Price Guide.

I don’t know which retail comic book stores are the most reputable, but the field is so competitive that any shop that’s been in business for more than a decade almost by definition must be trustworthy.

You might also consider posting in a local neighborhood forum. We have a group of neighbors who will answer anything from where to donate books to who to call for a bad stain on a carpet. These people want to be helpful, and the odds are good that they will know other people interested in comics.

Good luck! It sounds like a fun and interesting adventure.
Kate