Well I this is hard to believe - I installed version 2014.9.0.2008 and it automatically updated to version 2014.9.0.2021. This is the worst version of Avast I have ever used.
Something may be wrong with your system, because none of the things you described apply to the 2014.9.0.2021 that I'm running, and I'm sure many others here.
Beyond that, it's really not reasonable to run an old version of an antivirus package. The sense in running such a package is that it's up to date with the latest detection wisdom of the antivirus company. Yes, the old version might detect old malware and protect you, but it's not going to protect you from the newest badware out there.
I suggest you do an uninstall and clean install of 2014.9.0.2021, then work out whatever kinks you find (which may be none at all once you've done a clean install of the current version).
Edit: By the way, I went through a bout where an update went badly, late last year I believe it was, and sure enough a clean and install of the latest version corrected all the problems. I really think your assumption that you want to go back run the old version to avoid all the problems is way wrong.
-Noel