Monsters in D&D can have multiattack before players would get Extra Attack (iirc monsters as low as CR 0.5 can have multiple attacks, and those are monsters that should be easy for even level 1 characters to deal with).
Yes ...
Mostly Druids in Animal forms ...
Funny that they didnt get it, but Goblins (who never had such feature to my knowledge) did.
Also, Githyanki being able to cast and attack at same turn, sounds simply straight forward broken to me. :-/
I dunno ...
I remember Swen braging about how extremely dificiult their Tactical mode is, i believe he said something like "you will try it and you will die and you will be angry, but that is on you" ...
No, Swen, this is purely on you!
I know you like cheesing things, but if you need to give your party unfair advantages in order to make them threat, you failed as a Game Master. And its not even Tactical mode. -_-