Hey guys, how can I get the most out of my telescope? f/4, 100mm reflector

Last month I got my first telescope and so far my favorite thing to observe is Jupiter. I can see the big 4 moons around it, but they only appear as tiny pixels. This is when I'm using a 10mm eyepiece. I was wondering what kind of eyepiece I should get for viewing planets better. The scope came with a 25mm eyepiece also- is this a good size for checking out deeper space objects and galaxies?

One more thing about collimation: My scope took a small tumble out of my car door during a trip (my friend's fault), luckily nothing is damaged or broken. I probably need realign the mirrors, right? I read somewhere that little bumps from walking around with it or even transporting it can mess with the mirrors.