The Stat of Limitations expired for federal, but not for NY state, where they have 'tolling' law, meaning when you leave the state, the clock stops and doesn't start until you come back, hence the indictment on state charges. However, on the face of it, it's a misdemeanor and I hope he finds a felony or two in the mix, otherwise, this charge will fall flat on it's face.
Correct, hush money is not illegal. However, given that he reimbursed Cohen for payments he made, at the direction of, for the benefit of 'individual-1' (as named in Cohen's indictment, for which he was convicted and served time) where the charge is a felony campaign violation, given that the evidence shows the payment was made for the benefit of Trump's election campaign. Now, at the state level, there is a crime here, but as to the specifics, we'll have to wait and see.
I don't think they would empanel a grand jury for a misdemeanor, so I am curious to find out what the actual charging document will look like.