Last night I looked for a way to disable Metro in Consumer Preview, as I did in the DP -- and it appears that Microsoft has deliberately disabled the registry hack allowing you to do so for the CP.
They continue to claim that the release version will let you perform the switch more easily.
Otherwise, concerning the Start menu thing -- I have been unable to find a better solution online than my toolbar trick
There is a chance that it may be possible to actually move this toolbar into the "start button" spot on the taskbar, but I have been unable to discover how to manage this.
Other sites advise people to install some 3rd-party software originally designed to provide a Vista-like start menu in XP. hmmmmmmmm, I am very wary of such an idea.