Yes, they can connect racks via gigabit if you need it. They also can setup the racks in a redundant manner so that you have 2 20 server racks with 2 load balancers (each from different providers) and 2 different power supplies. It will of course cost more, but the options are pretty big when you deal with the private racks and do not hesitate to ask about even off the wall ideas you would be suprised how many things they can do

The email ryan posted will be your best way of contacting ev1 to get the prices and availability of anything custom.
If you want feel free to pm with any questions if you want a customers perspective on the racks, or post them here. I have worked extensively with ev1 with private racks, the load balancers, as well as some custom setups for clients. We also have a few clients with multiple racks all serving a single website, it is very possible to do with the hardware they have.
They also have a special support network setup so that if you do have problems you can very easily get hold of the same floor tech that can go and investigate it.