Once you engage your quantum drive, are you guaranteed to reach your destination? Are there any dangers inherent in such travel?

You're definitely not guaranteed to reach your destination. It will actually be pretty common for you to be kicked out. If you're trying to cross half of a star system, you're probably going to be kicked out at least a couple of times. That will increase or decrease depending upon what's between you and your destination point. If there are large battles raging, if there's a significant force of pirates, there could be meteor showers, micro black holes, dark matter nurseries, just a variety of different things that can basically cause your navigational computer, which cannot make quick course corrections to chart you around these things, to wind up engaging essentially a safety mechanism, kick you out of quantum travel, and at that point you need to just navigate your way through that, around it, a different course, et cetera.