The Tommies likely have more money at their disposal than any other team in their conference should they choose to steer it to hockey. I would guess they committed to build a rink as soon as it was feasible. I'm not aware of any special arrangements that were made for them to join. It's a hockey crazy state and they're a private school with wealthy alumni and a tradition of successful hockey at lower levels. It shouldn't be any great challenge for them to get a facility funded and built when they find the right solution/location.
Just because they have a huge endowment doesn't mean they can throw money around like there's no tomorrow. They don't get public money to operate, they have to fund themselves through tuitions and that endowment. Like every other school in the new CCHA, the program will likely require a lot of funding from alumni and boosters- more so than the public universities. And I wouldn't focus so much on their facilities for now. What would be interesting is who they hire to run the program and how much they pay him.