Format question

Im planning a tournament of 3 groups with  4 people each where top 2 qualify for the next round.

1. How will the matches be selected for the next round??

2. is it going to be a knock out stage ?

3. Will in the next rounds and the final, 2 matches will take place? (one with black and one with white)

All rounds have the same format.  http://www.chess.com/tournaments/help.html#groupings

"For multi-group tournaments, players are placed into groups starting with the lowest rated player sequentially up to the highest rated player. For example, in a 25-player tournament with 5 groups and 5 players in each group, the lowest rated player goes into Group #5, 2nd lowest rated player into Group #4, 3rd lowest rated player into Group #3, and so on. After all groups have one player, it starts all over again at Group #5. So, in this example Group #1 would have the following seeds: #1, #6, #11, #16, and #21. This is done to try and ensure that in the final round, the best players will be left playing for the tournament win."

I fixed the explanation, in red, so it works where groups are not all full.

For subsequent rounds all the advancing players are seeded again and placed into groups as indicated above. This continues until only one group is left in a round.

Example tournament:  http://www.chess.com/tournament/b60-sicilian-defense-richter-rauzer-variation-thematic-tournament

Your round one will be similar to this:  http://www.chess.com/tournaments/pairings.html?id=10332&round=4

Your round two should be similar to this:  http://www.chess.com/tournaments/pairings.html?id=10332&round=5. Notice there is a limit on players advancing. Maximum 50% of the largest group in a round can advance. So only one of three advance.

Your round three should be similar to this:   http://www.chess.com/tournaments/pairings.html?id=10332&round=6

many many thanks !