I use the Activadose II. To transform it for tDCS you need to buy standard TENS wires (I got mine on amazon.com for like $2), sponge electrodes, and some "pin to banana" connectors. I used the information on page 3 (I think) of this thread. I'm sorry...but I don't know the answer to your other questions.

If you have any other questions about tDCS, please ask or feel free to PM me.