The configuration is pretty easy to follow, and while there are a good amount of parameters to shape your tone, it won't take too long to get a sound you are happy with. It is easy to follow all of the options and there is a lot you can do to your tone with the given parameters. I don't have a manual for the Mesa Boogie Mark III, but it is easy to use and you shouldn't need one if you don't already have one.
The Mesa Boogie Mark III is great for all types of music, but I use it mostly with rock and blues, as it feel it works best with these genres, and this is mostly what I play. I use this amp with either a Fender Stratocaster or a Gibson SG most of the time and usually use it without any effects. I find that the built-in gain and EQ are enough that I don't need any extra pedals most of the time, unless I want delay or modulation effects. Overall, the inherent tone is outstanding, especially for such a small amp.
I've been using the Mesa Boogie Mark III guitar amp for about four years and it is one of the best little amps I have used. The tone is awesome, as it is full bodied and sustains very well. Mesa Boogie makes some great amps, and I believe that the Mark III is one of their best deals. Overall, a great amp for recording, practice and live shows.