Don't stick the mic inside the drum. The audience does not want to hear the inside of the drum. I have a ported kick head and I stick the mic right in front of the hole and I get the sound of the kick, NOT the inside of it!
Well, for class we've always gone inside the drum, and at least with the D6 it sounded phenomenal. I'll experiment, of course. I've got the hole now, and it still sounds great live (maybe better? it's hard to tell) and it seems easier to play, too... I might just be imagining that, though. Drums always seem easier to play every time I come back to them after not playing for a while. I have no idea how that works.
Depends on the audience. Some audiences don't even want to hear a real kick drum. Most of the time, the audience doesn't know the difference.
Different mic placements, tunings, and head configurations will give you different sounds. The style of music and your technique will determine which method will work for you.
For example, a kick with no port hole and a d-112 in front of it will not work in a death metal context. No matter how much we all love John Bonham, his sound will not work in every situation.