MTG Salvation

So, Adapt 1 is Monstrosity 1?

Nearly. While Monstrous cares if a creature's Monstrous ability has ever been activated and resolved, Adapt only cares if the creature has +1/+1 counters, and can't properly resolve if they are present regardless of how they got there.

A Monstrous creature can have all it's +1/+1 counters removed and reactivate its Monstrous ability, but nothing will happen when it resolves. Adapt creatures on the other hand can reactivate the ability, and so long as it has no +1/+1 counters on it, will receive the appropriate amount.

We are sure to see a lot of cards out of Simic with interactions involving moving counters amongst creatures, maybe even some without Adapt. I'm also willing to bet we see a card with Adapt paired with a "Remove a +1/+1 counter:" ability, allowing it to reactivate Adapt multiple times on it's own.

Limited bomb. 2/3 with flying for 3 mana, then pay another 4 to give it a +1/+1 counter.

I am worried about adapt, mostly because all I have to do is have an instant-speed way to put a +1/+1 counter on a creature to counter your adapt. Damned intervening if clauses.

That's a very, very expensive +1/+1 counter, but a good base statline plus makes this a good limited uncommon.

Yes

The card is common.