1.) Not possible.
2.) Nope! If u do it from command prompt, it'll just change the extension of the file but the format will be same. So use the available converters for it
3.) Don't delete those files/folders, coz they r used by avast! anti-virus. If u really want to delete them then u can use Unlocker to delete them. But it'll be of no use, coz after a reboot u'll get them back
4.) Type
sysdm.cpl in RUN dialog box and goto
Advanced tab. Click on
Settings in
Performance section. Goto
Advanced tab and click on
Change button. Now select
System Managed Size and click on
Set button.