Not a problem the mini comes with USB and Firewire so you will be able to hook up a keyboard and mic easily. As far as I know, the mini comes with iLife software so all the software you need for starting off in video capture- Audio etc is there for you.
Apple Quote "It Just Works. Manage your music for iPod or organize and share your digital pictures with ease. Connect your digital camcorder to Mac mini and start editing your masterpiece. Or plug in your electric guitar or keyboard and make music. How? With iLife, a suite of easy-to-use applications ready to turn your life into a digital wonderland. And Mac OS X makes it effortless — you won’t have to install extra drivers when you add hardware to your system. "
You want to go for the Superdrive option if you haven't already got a CD - DVD burner. It might make it easier for you, to make your own cd's and dvd's.
regards
Ric