Bonjour
It really depends on what sort of walks you'd like to do.
If you are into walking up the more difficult mountains, then Glen Brittle (this is the name that is used rather than Bualintur) or Sligachan are the best choices. Sligachan is easily reached by buses; there is just one early morning bus and one afternoon bus to Glen Brittle. Glen Brittle campsite has a small shop and nowhere to eat; Sligachan has a hotel near the campsite but no shop or anything else.
If you are looking for easier walks, there are good walks around Staffin and some near Dunvegan. But I think if you come by bus you'd be better camping at Torvaig campsite (one mile from Portree) and then using the bus each day to get to the start of walks such as the Storr, The Quiraing, Dun Caan on Raasay etc. You can then walk into Portree to find places to eat and shops as needed.
Have a good trip, and happy walking