Seems like quite a good deal you got there, especially if the mount is of good quality
. An 8" can see more objects than you could possibly see in your lifetime so I think you will get a lot of good use out of it for many years to come. I have an 8" and I have had some great views of DSO's (from dark skys) so it is certianly possible. One thing you have to become familiar with is collimation. Reflectors require collimation every time they get bumped around a bit (If you move it carefully out to the backyard should be fine). Collimation is simply aligning the mirrors so that the big one at the bottom of the tube (The Primary Mirror) points directly to the centre of the small one at the top of the tube (The Secondary Mirror), and the secondary mirror points directly to your eye. There are a number of tools to help with this and make the job easy and a quick search of the forums will provide you with more info on the tools and the techniques. Welcome to astronomy.
P.S. I would recomend you spend a few months just doing visual work and familiarising yourself with the sky and the scope before you get into imaging, IMHO.
Leon