Unless he's eating food, which I have the distinct impression Alexi is going to deny him for the most part, there really is no reason for him to use the bathroom since a vampire would just absorb the blood, and if he really needs to use the bathroom Alexi will give him a chamber pot and some privacy. As for being chained, Alexi is ready to give him a longer reach of the chain, and occasional "Walks" with them with Joseph making sure that no one is around to see Erik. The reach of the chains will encompass most of the room at it's fullest extent, and Alexi has a library along with a wide variety of old toys and gadgets which Erik will have access to basically right after this talk. Make sense?