I'm pretty active on the forums so you can get a grasp of how I work from my activity here and here's a link to schedule a free half hour call if you'd like.
> creating a form that will populate 2 tables For this you would need to use an automation I believe. You'd have your automation trigger when the form was submitted, and it would have a "Create Record" action that would create a record with the exact same data. (If you don't need to modify the data I would recommend you use a linked field and lookups instead)
> creating a form that will update information on a table. (not overwrite) Hm, so you would want the field data to be something like this?