Hi and welcome, Canuck. You have picked a good time of year (usually) as September often has nice weather, with balmy autumnal days and slightly frosty nights - just enough to kill off the biting insects. Sounds like you have it sussed on the access/camping thing. Keep away from people's homes and property or they may disapprove. Bury toilet waste and carry out rubbish, you know the score. Kingshouse Hotel is dead, unfortunately, but up the hill from there is the ski cafe/bar which stays open through the summer and has a small campsite with camping pods too which you may wish to resort to if the weather turns lousy.
http://www.glencoemountain.co.uk/accommodation/ There are pubs which do meals at Clachaig and Glen Coe Village, further into the Glen (about ten miles down the road - hitch hike there). Water is generally ok, better to get water from small fast-flowing streams coming down steep slopes rather than the main river.
September frosts are usually mild, just dress well for it and you'll be fine. A three season sleeping bag should be good enough.
Baggage transfer sounds a bit pansy if you're camping; you don't need to carry a week's worth of food and heaps of kit.
My advice would be - take three pais of thick, padded, knee-length socks.The kind with extra padding around the heels, toes and soles. The path is very stoney and hard on the feet. Stop frequently and indulge in the old Scottish hillwalkers' habit of taking off your boots and socks and bathing your hot feet in the burns that come foaming down the hillsides. Bring a sunhat in case it's sunny, and a warm hat in case it's cold. Leather work gloves are good to stop the hands getting cold in the wind. Chapstick to protect your lips from drying out, packets of paper handkies instead of a roll of toilet paper, and a small thermos flask so you can fill it while you're camped and have hot drinks through the night and when on the move, without having all the bother of getting the stove out and boiling water each time.
- Weather approaching across Rannoch Moor
- Rainstorm sweeping across Rannoch Moor.
- Blackrock Cottage, Rannoch Moor. Buchaille Etive Mor in the background.
- Camping at Kingshouse