The MPD 26 is pretty basic and easy to use, I'd doubt you'll need the manual much. It's only a midi controller and I don't know what software comes with yours, but you'll probably need to familiarise yourself with some kind of DAW (digital audio workstation) like Logic, Ableton, or a free app called Reaper. Something that will act as the sampler/sequencer that a full MPC has built in. Learning the ins and outs of that will take more of your time, in fact it's a constant learning curve pretty much. but these days there's plenty of great online info & YouTube videos to help guide you through from set up to mastering. Don't get bogged down in it, but picking up good practices at the start can save you a hell of a lot of time in the long run.
I've been messing with Ableton the last few years and think it's great, very user friendly. You can put a loop into ableton, select 'chop to midi', select the size of the chop 1/16 ect, and it will put your samples in an MPC style 16 pad sampler ready for you to play.
I know several people on here use Logic. Don't know if anyone's ghetto enough to be rocking Fruityloops, but I'm sure whatever one you choose someone here will be able to guide you the right direction.
I'd look into getting a cheap midi keyboard. You can pick up a decent one pretty cheap, you're more constrained by how much space you want it to take up. They go from the full range with weighted keys, if you want that piano feel, to some pretty good portable ones the size of a qwerty keyboard, which will work fine if you're playing in basslines or simple melodies.
Lots of midi keyboards try and sell you on the fact that they have extra knobs and sliders, but you already have those on you're MDP (which can be midi assigned to control pretty much parameter in your software, like filters, volume levels, delays etc) so you don't really need them on keyboard too.
As you've started with a midi controller, for now I'd recommend staying 'in the box' (using your computer for everything), you can get a very professional sound with digital these days anyway. Once you start trying to incorporate hardware synths, effects, etc things can get complicated and expensive pretty quickly.
Software can get expensive as well though, unless you're down with pirated software. Either way there is a world of music production software out there. You can also get a pretty good set up going the freeware route, especially if you're on a PC. You'll probably want multiple soft synths, effects, meters and mastering tools ect ect. A good DAW will come with a lot of it's own though and you can build on that as you learn and grow.
