Based on current calculations they predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance. They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.
There are actually a bunch of stars that will pass by very close to the solar system in the far future (tens of thousands of years) and they could possibly increase the number of asteroid and comet impacts drastically.
It could set if a wave of supernovas, though, which would be bad for anything living in either galaxy. AFAIK our understanding of the process isn't good enough to know.
Nah, we will build a stellar engine prior and move ourselves wherever we want. We will have colonized all the Milky Way and most of Andromeda. It'll be like a brother and sister finally meeting near the washer.
Space is so vast that the Earth and Solar System will survive.
Although the galaxies will plow into each other, stars inside each galaxy are so far apart that they will not collide with other stars during the encounter. However, the stars will be thrown into different orbits around the new galactic center. Simulations show that our solar system will probably be tossed much farther from the galactic core than it is today. Source