Hopper DIY

I am considering upgrading to the Hopper system with one hopper and one joey as I plan to add additional joeys and an additional hopper by buying them on the marketplace. I talked to the Dish Rep (chat room) and asked if the installer would install a Duo Node (in place of the single node) plus add 2-Taps (in place of slitters). The rep also stated I have the Pro Plus dish. Will there be a monthly charge on any additional joeys and hopper from Dish? Will Dish allow me to self install these additional units? Your comments are appreciated and await them before I upgrade. artholl