Theres one galaxy on universe
Millions, although the answer obviously various with factors such as the size and species of mushroom.
There's one real expansion which is Galactic Adventures. There is also a "content pack" Creepy & Cute which gives you some additional parts to use on your creatures along with some new animations.
less and less every day
you can probably have 3 since once you make one profile it says profile 1/3