Yo Suds:
A drum machine works with presets for one. You push some scroll buttons and the preset title pops up; if you want to hear it, you push "play." Some boxes have over 400 presets. The sounds are/or can be: Funk, Latin, Pop, Ballad, Jazz.
Also, you can program a drum machine with your own loop. You can do as many bars as you want, tweak it, play it back and decide if it's what you want. It takes "time" to program a drum machine so many of us use the presets.
Midi? Yes, a drum machine can be used that way if it comes equipped. Most drum boxes do midi.
There are several drum boxes out there: I use the Boss 770, a great little box. You can patch your drum machine into your board or recorder/ mono or stereo.
There is usually a pad board of some sort on most drum boxes and you can add more drum chops onto other tracks.
See if you can visit a vendor and demo any drum box in the store just to give you an idea of what's what.
And, Suds, you aren't a retard; it's a long learning process and that's what is so much fun recording -- learning a small "byte" here and there.
Green Hornet