Place nickle/quarter sized pools of it on the cardboard cutouts it comes with on the box or aluminum foil. Let them drink. Check it every couple hours the first day and refill the spots as needed. Can take days depending on how many there are.
I have had good luck with Terro. Though I never had a problem that bad. It takes a few days to get working, as it is designed for the ants to bring it back to the colony as food, before it kills them.
Dunno about your other questions.
Edit - A letter