John -
Each division winner gets into the playoffs, and are automatically seeds #1 thru #4 in the conference. Then, the two teams with the next-best records get wildcards in each conference. Total of 6 teams per conference get in.
From there, the #1 and #2 seeds get a first round bye. #3 hosts #6, and #4 hosts #5. Teams from the same division CAN play each other in the first round, unlike baseball where they cannot.
The next weekend, #1 hosts the lowest-ranked winner - either the #4, #5 or #6 seed. #2 hosts the other one (#3, #4 or #5).
So in the AFC, between Tennessee and Indianapolis, one will win their division, but the other can do no better than being the #5 seed, and will not host a playoff game (unless somehow #5 and #6 make it to the conference finals - not likely). Conceivably one of them could go 13-3 and then would have to win 3 straight road playoff games to make it to the Superbowl. Meanwhile Baltimore (or someone else from that weak division) is guaranteed to be at least the #4 seed, and WILL host a game. Doesn't seem really fair, but that's the way it is.
Tie-breakers: I am not sure about this, but I think when you are breaking a tie to decide who wins a division, the first tie-breaker is head-to-head play between the teams, and the next tie-breaker is record in games within the division, then record in games within the conference, record outside the conference, then it comes down to points scored or points allowed or something.
When breaking a tie between teams not in the same division, I believe it goes 1) Head to head play (if all tied teams played against each other), 2) Record within the conference, 3) Record against the other conference, pts...then, I don't know.
If more than 2 teams are tied, and a tie-breaker resolves only part of the tie, then it reverts back to the first tie-breaker with the remaining teams. IE. Three teams are tied for the #2 seed. After two steps teams A and B are still tied, but ahead of C... C is given 4th, and then A and B are compared again starting from the first step, if you follow me.