re: Other galaxies
In many ways, we know other galaxies much better than our own, as we live right inside it and our view is blocked by a lot of stuff. For instance, the average number of spotted supernovae is much higher throughout the universe than in our own galaxy.
Our galaxy might have a dual nucleus (or more); we know there's something emitting Gamma-rays 300 light years away from the center, and not right in it.
Colliding galaxies could indeed shape them into spiral ones.
Raoul