Inhabitants: I'm not into agressive tanks, so hopefully somone else can chime in on your eel and companion question.
Moving: I've moved my freshwater tank about 10 times between Chicago and Rochester. It's a 14 hour drive. Chicago to NYC would be a 20 hour drive? 20 Months would be November?
Bring as much old water as you can. 5 gallon buckets will cut down on your gas milage, but reduce the shock of the move.
If possible, pre-mix a large amount of saltwater at your destination, so you can do water changes right after the move if necssary.
Seperate fish, invertabrate livestock and live rock into seperate buckets, or see if your LFS
will pack them in bags and styrofoam for you. (If bagging, pre-arrange, but leave this step til last minute.)
When draining the tank, take all but the last couple inches as your clean water you're bringing with you. Stir up the substrate really good to wash it and siphon the last bit of water as waste.
Pre-plan disassembly/reassembly of your setup so it goes as fast as possible.
If you have to stop for the night, bring the livestock in to the hotel for climate control reasons.
If you can do everything fast, keep everything wet, and not let anything get too cold/hot, you should be able to set up at your destination and not even go through a second cycle.