5 and 7 year old don't generally need too much baby proofing. I think the key is that you provide lots of storage to keep down clutter and so they don't step on stuff and break them. At this age, they should be able to keep this room clean as long as you give them places to store stuff. Avoid stuff with glass. Carpet is better than tile, if tiled, then put an area rug. Easy to clean furniture. Don't invest too much on kid furniture. They outgrow them too fast and then they become useless. A table and seating for crafts or drawing.
I think that if my 5 or 7 year old got injured rough housing, then they learn a lesson not to do that for next time.