How is Portugal in February? Are museum/tourist attractions etc. open? Wet or cold?
Of course everything is open! However, your chances of rain are higher than some other times of the year. As far as cold - depends on what you consider cold. The highs most winter days are at least in the mid 50's with quite a few days in the 60's. The days without rain are glorious! The skies are much clearer than during the summer and, with fewer tourists, it's a great time to be here.
Also, I'm only speaking for the Lisbon area. The Porto area and north will be cooler with more rain.
When I asked if everything was open I meant museums, theater, etc
You will get better advice if you provide more information about your interests. February is the off season for the beaches - not recommended. On the other hand, this is a good time to visit the cities because there will be fewer travelers. "Everything" will be open in February.