Does Faceless Haven Have Summoning Sickness?

Faceless Haven should not come onto the battle field with summoning sickness. Its not a creature, it is a land and should be able to be played instantly.

Can you attack with Faceless Haven?

Although Faceless Haven will have all creature types after its last activated ability resolves, it will not have the changeling keyword ability. If Faceless Haven becomes a creature but hasn't been under your control since the beginning of your most recent turn, it can't attack or be tapped for mana.

Is Faceless Haven Monocolored?

What does that mean? It's an indicator that they are best for one- or two-color decks, likely aggro or aggressively slanted midrange decks. But even more so than Mutavault, Faceless Haven entices you to play a monocolored deck.