RE: Removing Tape Hiss
I use the Cool Edit Pro/Adobe Audition noise reduction tool for this.
It used to be that you could get this more cheaply by buying
Cool Edit 2000 and getting the noise module as an add-on, but
Syntillium shut down CE2K when they sold out to Adobe.
Audition will cost you more, but it's still a pretty darn good audio
toolkit for the money.