I really wasn't happy about two slots going to companions, we already had in two games. I never liked Minsc and I don't know what more there is about to learn from Jaheira. I really hope, we don't get more recycled characters.
And I don't want to loose the companions, not currently in the party, after act 1. That is a really stupid mechanic.
Both points I very strongly agree with.
On the second point, if this mechanic remains in the game, what happens if at the end of Act 1 you choose to dump all five origin companions and have no origin companions in your party and have only your custom PC? Wouldn't you then need a minimum of three companions available in Act 2 to form a party of four?