on my system, i have:
Mozilla (Gecko engine)
Mozilla Firefox (Gecko engine)
Opera
Konqueror (Gecko engine)

i use firefox the most...been using it ever since it was called Firebird ...occasionally i might fire Konqueror up.

by the way, you can ctrl+click on a link to open it in a new window. saves a lot of time if you're in a rush.

as for the temporary files, i can't really remember what the path is on Windows but it's mentioned somewhere in the Firefox page at mozilla.org if i remember correctly. if not (it probably is), google is your best friend