AlegroCart

I've been unable to find which payment gateways Alegro supports. Kindly direct me to them. Also, Moneris eSelect (http://www.moneris.com/en/Products-Serv ... teway.aspx) is the largest credit card processor in North America, if it's not among the available gateways, can it be added?

You can find supported payment gateway under admin/extensions/payment.
Moneris eSelect can be added, it is only question of time.