i'd second what BS has said - limited number of paths, and where there's no path its very hard work - and its absolutely infested with midges.
its a fantastic area, really worth the effort to explore - but i'd say that early spring and late autumn would be your best bets, but it is hard work. the terrain is deeply lumpy, and if you go at any point where you aren't going to be eaten alive you're going to have to work hard on your river crossings and often go well out of your way to find a safe crossing point.
bothies at the western ends of Glen Dessary and Glen Pean - but hit the Mountain Bothies Association website for current details and locations. Inverie has a pub, it used to has a post office but i'm no longer sure if thats still the case - if you decide to use the bunkhouse there for a 'halfway point' i'm reasonably sure they'd be ok with you posting supplies to them for you to pick up there.
its a reasonably committing area - while there are people around you'd want to be careful about betting that they'll be around when you need them. you also need to be aware that the ferry can be cancelled by bad weather, and that bad weather is not unknown in that area in late Autumn/early Spring. its one of the few places in the UK where 'light' vs 'heavy' really is a debate worth having with yourself...