To set IE 32 as default. You say restore your system to 32 bit IE - you mean the IE browser I assume not the operating system?
Click on Start and go to Default Programs. Click on Associate a file type or protocol always open in a specific program. Browse to all the extensions where internet explorer is set as default and then click on change. Now Click on browse and then go to location C:\Program Files (x86)\Internet Explorer\iexplore.exe and select it. Click Ok and then Close. Click Save.
There shouldn't be any problems because your have Windows 7 64-bit if you make sure that you are downloading compatible programmes.
Equally there shouldn't be a problem with Firefox. Are you sure that you were using the current version of Firefox and the correct version of Adobe Flash Player for Firefox as there are other options?
What are the "glitches" you mention?