Re: costs
To the best of my knowledge, the CBO has yet to analyze the current Senate bill.
Anything can be "solvent" if you assume massive levels of taxation, and that the new taxes will have no effect on productivity. The real world doesn't work like that.
As for me, I prefer to go by experience, and that says that any large government program - ironically Medicare comes to mind - will end up costing far, far more than predicted at its outset. So far, I have seen no exceptions to this.