I don't know about importing a sample and getting a crash from that, maybe thats a different problem, this has never happened to me. I maybe recall once or twice it happening with those really bad samples from the net with weird bit rates and pcm audio etc For the time stretching thing as I said before I simply bounce in place or convert to new audio file as soon as I import to avoid this problem, works great, the thing is I'm so used to doing this even if they fixed it I would probably continue doing it out of habit. You can also avoid the crash by switching flex mode on but really bouncing in place asap is better. Also I believe its better practice as you have more copies of your original file. I also believe that if you import an mp3 this will not happen as logic converts it anyway so then you can skip the "bounce" bit.
With the pin wheel thing I was told of a trick by a graphic designer where he would just leave it for about 20 mins, go and make tea or something and on a rare occasion it would come back but that was with photoshop and have only tried it with logic once and it didn't work also the fans were going hell for leather, as I always Apple/S I usually just force quit and away to go.
Im on 9.1.6 and its still happening so I don't think there is a fix yet but again I don't see it as a major problem as it has an easy work around.
Logic 9.1.6, OSX 10.7.5
2.4GHz quad-core Intel Core i7 4GB 1333MHz