Norton Firewall for Mac Question

Hi, I am new to Macintosh, and the reason why I switched over was because of the level of Malware for PC based cpus were ridiculously high.  I have two desk top pcs, 1labtop pc, and one mac now.  I Finally found a way to fix my pcs, this was done through flashing the bios, buying a new hard drive, and reinstalling everything.  That was the only option.  I hope I never have to face such problems with Mac, and therefore against all advisors from Mac store, I purchased Norton Internet Sec. 4.0.  I have noticed that I have no printer for my mac, and the fire wall keeps giving me a message about sharing printer.  I am using one of the new IMacs, and is this something normal?  Also do Macintosh cpus have a bios as well? or CMOS?