I note from the other thread that you're feeling overlooked. Forget Scots being argumentative (I strongly disagree with Murray about that). Your itinerary looks good to me. THe islands are a great idea. Don't know if you've been before, but there are festivals on Arran, Bute, Skye (I think) and the Hebridies. I'm not an expert but I'm pretty sure you can travel to Harris for the Hebridean FF from Skye which is worth visiting as its beautiful.
Glasgow, definitely warmest people in the world, I'm sure they'll make you welcome. (There is a flip-side to that that people dwell on in an attempt to be humorous, but no more of a problem than any other big city)
If you're in Glasgow make sure you nip through to Edinburgh, its only 45mins by train, see the castle, Holyrood Palace etc I've pointed out elsewhere it has the biggest arts festival in the world. I have been corrected that this no longer has a folk music section. This is in August so I don't think it will coincide with your trip. Its worth a visit anyway as Edinburgh is usually buzzing
Failte
Z(R)