About 30.
They make up approximately two thirds of all known spiral galaxies.
yes
There are an estimated 1011 galaxies in the observable Universe. Please note that the entire Universe is much bigger than that, but it is not known how much bigger. It may, or may not, be infinitely big, in which case there might be infinitely many galaxies.
NO! galaxys are many thousand times bigger than our solar system
At its centre.
Ultraviolet
The path of univers's galaxys
The center of the elliptical galaxy is very dense with many stars, and density decreases farther out.
It makes sense to talk about the climate on other planets, not on other galaxies. Not much is known about the climate on any planet outside the Solar System.
See related questions
the milky wayis the galaxy that our sun is in