It's complicated by the fact that with 1 trial, there is a 0% chance that the house will take within 1.89 to 1.91 percent.
The chance is not 0%, but it is very small, perhaps <<0.001%.
Wrong. Let's say you bet 2 BTC once on the 50/48.1 address. There are only two options:
The house gains 2 BTC (100%)
The house loses nearly 2 BTC (98.1%)