I can give you a little information! Portland has little hills and they get to be a little more rolling the farther inland you go.
I highly recommend riding up around Sebago Lake (30-40 minutes N of Portland). The lake is fabulous and the roads are far less cramped with cars.
Weather is hard to predict... could be rainy, could be sunny. By that time of the year the ocean starts warming up and the lake is a beautiful 68 degrees or so.