Yes to all your questions. You can have one copy of a single colored card per 50 cards in your deck. And I believe entrappers are generic.
The Entrapping Pharisees are unique not generic.
Also, you may have more than one copy of a single colored card per 50 cards in your deck, so long as that card does not have a special ability. For Characters and enhancements that do not have special abilities, you may have up to three copies of them per 50 cards in your deck. For sites without a special ability, you may have as many copies of those sites in your type I deck as you have souls.
For single color cards with special abilities, artifacts and fortresses you may have 1 per 50 in your type I deck.
