A few things:
-As is, there is no cap on how many minions you can have. Even if this was intentional, I have to disagree with this vehemently. If you don't want the class to be broken from the get-go, you need to have a maximum number of minions.
-As written, the level cap on evolution points in a single evolution does not apply to Infested, Assimilated, or Embraced.
-When and how do you apply Evolution points? Do you simply apply them when you get a level and then have to wait a level before your minions improve, or is there a ritual? Can you redistribute Evolution points?
-The bonus points per minion does not specify which ability score they are keyed off of.
-I think the evolution costs might need to scale just a little bit faster. Not sure about this one, though, as I'll have to do some maths.
I might be forgetting a couple, so I'll try and remember them later on.
EDIT: Oh, yes!
-How does one go about replacing a dead Swarmling? Also, when it says you turn an Infested or Assimilated into a Swarmling instead of just making one, how and when does this happen? Is it when you gain a level, or is there a ritual?
Aside from those, it's pretty good so far.