You’re paying $75 total for three rolls of film. If you take photos a lot then buying a cheap modern mirrorless camera (DSLRs are dated) will definitely be cheaper.
Two great free photo editing software’s are Darktable (editor and photo manager) and PhotoGIMP (a patched version of GIMP to make the UI similar to Photoshop). Bruce Williams on YouTube makes great tutorials for learning how to use Darktable.
Since you are primarily taking photos of your kids I suggest saving some money for a cheap hotshoe flash. It’ll really benefit photos of people.