"Bill" is not an idiot, and he knows you want to preserve the dates on your files. You're looking at the "Date Modified", and Bill has accurately recorded your key strokes. Rt-click the column...

Rt-click the file/Properties
Choose "Summary", enter away.

Yes.
In folder one, select all/rt-click/rename
Enter an appropriate name (i.e. my vacation)
All will be renamed "My vacation001, etc.
Irfanview also has a batch rename utility.

If you have have an actual install CD you should be OK. You can't actually delete any files from it.
Boot from the CD and follow the install prompts, including formatting the disk.
If you need more...

The file association has changed.
Right-click the file, select "Open With", choose program.
Check the "Always use..." box.

Select the pst file that's stored under your old account name and use the import feature.