Well it looks okay in specs but I think you have to actually hear/demo something before making up your mind. This sounds pretty generic but it is the only way. Because only you can decide what works best for your needs. ... And of course we all have very different tastes and needs.
I personally use soft synths and samplers for drums. I have:
NI Battery (for electronic/dance drums)
DFH Superior with vintage ad on for acoustic drums.
.. and Apple EXS 24 sampler along with Ultrabeat. Both come with Logic Pro.
Some of my hardware synths have pretty good drums too. Even the VIrus TI that I just bought.
Anyway. I wish I could answer all of your questions but I'm not a dealer and can only speak about things that I use myself. I think you'll have more fun with software synths than you will with just the MicroKorg but at the same time nothing is stopping you from getting it now and adding all the software stuff later.
I mean you have to start somewhere. If I were you I'd just go and pay a visit to the nearest music store. Talk to a few sales reps and check out what's available.
-ED-