Porting is grinding and enlarging the the intake and exhaust opening on your cylinder head to gain optimum air flow and exhaust discharge. Polishing is like the word says, which is basically smoothening the grinded area for better directed air flow. A 3 angle whatever... as you mentioned pertains to the valves. Most stock cylinder head comes with a 3 angle valve job already. It is the angle of the valves itself relevant to the angle on the head for sealing purposes, very critical. When you upgrade a "head", (think car now guys), these are the things you'd want to do, of course there's way more shit to the list I can add, but this should basically answer your questions.