I have medium arches and sometimes feel as if harder-soled shoes don't offer more support. i am considering purchasing shoes .5 size above my normal size (10) and using insoles more regularly for more support. would you suggest this?

If you ever have mid-foot pain through the day you may need proper arch support. Inserts/arch supports are readily available through foot specialty stores or a podiatrist office. You may be better of long term by having a filling at a foot specialty store or podiatrist. Your idea is not unreasonable.

Do not waste your time and money going to a store for medical questions. You have many questions and concerns. See a podiatrist and have it done properly instead of guessing.