For best results on Linux, usually the latest anything is best avoided, while issues are worked out. It depends though, and things are improving a lot.
True, although intel have been very good about this in the past, and to some extent still are - there are often drivers in the kernel and in X.org for IGPs which haven't even been released yet.
I've also run into regressions on older hardware that no one cares to trouble-shoot because not enough people are on the setup (e.g. the soundcard on a PowerBook 667MHz for example).