Heres an indoor render
Also heres an interesting quote:
“We would get the residential up and running, and we would get the Celtics up and running, and we’d get those buildings and (the arena) permanently financed, and then we would turn our attention to the track and field and probably the hotel,” Halliday said.
Link
Thats the order it has gone in so far, so hopefully that means after this gets built the hotel is next.
Also the track is going to be on the 3rd floor, which leaves a lot of room for the other things included like the sports lab, concert venue, basketball courts, retail..etc. Im sure the performance venue will have its own entrance at ground level and be its own separate entity from the sports complex or lab/retail.
Link