Holdem Challenge

A cardroom I know is offering a new game to its players: Holdem Challenge. Here's how it works:

Once you place your bet, 3 sets of hole cards are dealt face up. Out of these, you choose one hand as your holdem starting hand. A flop, turn, and river are dealt out. If the hand you chose wins, you get paid even money on your bet. If the hand you chose doesn't win, then the house collects your bet. EDIT: A split pot is a push.

How big is the house advantage in this game if you play perfectly (always choose the starting hand with the greatest edge)?


The following variations are possible. Which ones increase/decrease the house edge, and by how much?
1. Option to double on any pair.
2. Option to double on any ace.
3. A final hand that is a pair of aces gets paid 1.5:1 (at least one ace must be in the hole).
4. If you make 3 of a kind (or 4 of a kind) with a pair in the hole, the house pays 2:1.