A:AnswerIt can't connect via Bluetooth you have to use the included dongle. So if your tablet's plugged into a USB hub and the dongles plugged into the hub it'll work.
A:AnswerThe fob which comes with the keyboard and is plugged into one of the Raspberry Pi's USB ports is tied to the specific keyboard with which it is packaged. There should be no interference. If there is, separating the keyboards that do interfere across the room from each other should help.