I haven't heard anything about them offering the tablet but then again they will announce it once they start offering it.
As for the GIGABIT LTE speeds, as mentioned to you before. They haven't launched thag service yet. Once they do, they will release a list with the devices capable and which once they will offer it on. Unfortunately they won't give u the information u are looking for until the service has fully launched.
As for the OS Updates, they will offer updates untia a certain period of time. Unfortunately that can be at any given time. Remember it's Rogers and the manufacturers that both make a decision on when they stop supporting and updating the devices.