Several legal questions arise, imo, on gay marriage that I haven't seen asked just yet.
Not really. There should be no problems at all as far as the law is concerned. This is a non-existent issue.
1. The "maternal preference" rule has been abandoned in most states as far as I can tell.
2. The statutes use the terms "parent" and "spouse". I've never seen a single provision use the terms "mom" and "dad". The statutes are gender neutral.
3. Louisiana, along with most states, has moved toward "shared custody" as the preferred arrangement. If someone like SFP argues otherwise, he or she is full of shite. In fact, Jefferson Parish, for example, has become almost downright hostile to the idea of the mother being the custodial parent in the last couple of years.
4. It may be true that, statistically, mothers will have a slight edge when it comes to custody of very young children. But that's because a) more mothers tend to have given up, at least temporarily, their career in order to care for the child and b) most custody evaluators (child pychs./social workers) believe that the maternal bond is particularly important with children of a very young age.
5. Custody is decided on the "best interest of the child". Support is decided based upon relative incomes.
6. There is no reason there should be any difference with same sex couples.