That's me.
How long can I hold on to Windows 7 if Windows 8 is that bad? Usually a lousy release is followed later by a good release that fixes all the screw-ups of the earlier release.
1) I think Windows 8 is a fine OS, actually has some technical improvements over Windows 7. The only annoying thing about it is the mobile-looking "Metro" panel instead of the desktop/start menu everyone is used to. It's NOT a turkey like Windows Me or the (IMHO greatly overly) maligned Vista. However, you can get to familiar territory easily enough, and there are already third party products to make the look and feel of W8 pretty much the same as W7.
It has better performance than W7.
2) The current statement with regards to support from Microsoft can be found here, among many other places: http://www.pcworld.com/article/2010820/how-long-will-microsoft-support-windows-7.html It will NOT get shorter. As was the case with XP, it may well be longer. The short-take is that the level of support most people actually use will be be available until 2020.
I am on a W7 laptop right now, but run the W/8 evaluation on a 7 year old PC that was running XP, and if you run Classic Shell (http://classicshell.sourceforge.net/) on W.8 you should like it. It is rated slightly faster than W/7, even on older PCs (and the upgrade is only 43.00 til Jan 31. But if you have W/7 there is no need to change) But learn the hot keys (Windows key and “e” or “i” etc )