Heat the mandrel slowly as this lessens the tendency to flake and crack. Also make sure the release is thick enough when you're coating the mandrel. It shouldn't be too watery or too thick.. Thick enough so it doesn't drip, but not so think that it clumps.
Also make sure that you're heating the glass hot enough. Try working about 1" out from the head of the torch, with a little practice you'll find the 'sweet spot' where the glass goes like honey. It sounds like you're tugging at the glass, which makes it come loose from the mandrel and is caused by not heating the glass hot enough..
Problem 3 is also caused by not working in a hot enough flame. Try turning your torch up a little bit if it's not fully on, or as I said earlier, try working a little further out from the head. It can be the colour you're working with, too. I find that some of the reds do this. Sometimes the black is just a reaction to the heat and it'll settle back down but sometimes it's just not hot enough.
Certain colours (especially the turquoise ones with copper in them) have a tendency to discolour, too. What happens is that when the flame is too cold, the copper in the glass sucks all the oxygen out of the flame, turning it a murky red. Which can look kinda cool, sometimes, but is usually just annoying.
Some colours you just can't work with in the beginner's setup. I find that no matter what I try, I just can't get the opaline pink to turn out right.
Anyway, hope this has helped some. Good luck with it all, it is totally addictive and totally worth persevering!
P.S. I also find that flame dry bead release is handy. Just whack it on and dry it in the flame(slowly) and off you go. No overnight waiting.