Fax w/ HP PSC and Imac (Mountain Lion)

Hello, I recently hooked up my old PSC 950 to my new IMac (Mountain Lion). I used the computer's default drive, as there is no existing HP/Apple software for it. Do I need something else in order to fax and scan? Also, in Preferences
under Print and Scan>Options and Supplies >Driver, there is an option to check called "Duplexer" that says it will increase printer options. Is that relative?
I have a landline. I'm a novice at this. What do I need to fax? Thanks!