will acidic foods cooked in a cast iron skillet become Fe+2 enriched because of a reaction beteen the acidic food and the skillet?

Answer 1

Technically, yes. Practically, only slightly. Most foods are not that acidic, most are diluted with solvent (mostly water) and oils, and most skillets have been treated and/or used enough so the surface is coated with an oxide that slows any reaction with the skillet surface.