DC covered pretty much everything. Just know that if a security deposit is needed, the maximum is $400 per line. Just a few years ago it used to be a max of $1000 per line.

The minimum (according to a rep I spoke with over the phone) is $75 per line.

If your credit is in good standings, no deposit is needed at all.

Deposits are credited back to your account after a year of service granted you always pay your bill on time. I was informed that you also gain a small % of interest for being good with payments. Kind of a reward bonus saying "We know your credit was not good at the start, but here is a small gift of our appreciation for keeping payments on time."