I'm using a Rocktron Banshee now...
Love it...
Much better than the Dunlop one in terms of convenience...
As you have read in the above link, you'll need a preamp to power the the talkbox, then the sound of the amp will travel through the tube, and in your mouth, where you shape the sound by changing the shape of the 'sound chamber' in your mouth... The mic is there to pickup the sound in your mouth and amplify it through whatever the mic is running through, in many cases, the PA system... That means, when you want to practice with the talkbox, you wouldn't need a mic...
All in all, you'll need another amp to drive the conventional talkbox, quite troublesome... You'll blow your amp if you're not careful too...
The Rocktron one has an internal preamp built into it, so you need not to have an extra preamp to power it... All of the distortion will come from the talkbox itself, just hook it up just like any other pedal on your board, engage it whenever you want to use it...