I highly doubt that a Queen would change any more throughout her life once she had reached her adult stage. There would be no biological need for any further alterations to her being.
As far as a Queen's exact IQ though, it is not entirely known. Aliens themselves are quite intelligent, not to the extent of a human for example, but still apparently more intelligent than any animal living on Earth. They have a relatively basic understanding of how technology operates, but are still cunning enough to use that to their advantage, as shown in Aliens, when they cut the power to the complex right before their imminent attack on the marines. A Queen's intelligence overall would probably be a little higher than that of an average adult alien, although that is just an assumption judging by how we have seen them act so far.