That said, they certainly wouldn't have the same BI as everyone else, just as children wouldn't and the elderly probably wouldn't as well, since they have existing programs targeted to them. The idea is just to replace non-cash benefits within each group (those four are probably sufficient), and smooth out the payout curve and find the equivalent BI for that NIT.
CoL adjustments would result from this as well: the primary way this is currently done is via housing as you mention. Any housing assistance benefit can be valued like other programs, so that could then be disbursed as cash. In practice, this means layered basic incomes at the federal/state/local level, and if done gradually they could be designed to minimize evictions.
Those with addiction issues who would spend all their money tend to have mental illness, which hinders their ability to get benefits in the current system. I suggest retaining social workers for such circumstances:
> Some of these programs will likely be more effective than their cash value — especially those serving the physically disabled and mentally ill — and should remain intact.
One of the huge benefits of BI is that it's simple, you just give everyone the same amount of money. The more your start layering on exceptions, the more bureaucracy you'll create and you're back to square one.
The PwD piece falls more under healthcare (which I think should probably just be universal), so if their health-related benefits can be separated out, they would just get the standard basic income.
Retirees only need special consideration for political reasons, since social security may exceed basic income, but it could also be separated out into a supplemental amount to make basic income more universal. Ultimately they could converge to avoid special treatment.
And whether children get the same amount as adults is an open question among BI advocates; I don't have a preference either way and believe it should be studied empirically.
There should simply not be a 'PwD' element to BI - that should be a separate item altogether, otherwise it's just the thin end of the wedge. Leave it in healthcare-based welfare where it belongs, where both complexity is expected and health issues are better understood.
I would answer "yes" to your second paragraph, excepting possibly residents of Hawaii.
Regarding your third paragraph, we (society) already do tell a segment of the population "tough, you get to live on the street". Why is it so hard to believe society would suddenly find it unpalatable in this case? Basic income is nice, though, because it provides a path out of homelessness, and that's something that's often not present.
Also, what do you do about the difference in cost of living across cities? Do you take the housing allowance, give them a basic income and tell them to move if it's not enough?
And what do you do with the small number of people with addiction issues who just blow through the basic income and are left homeless? I highly doubt we're going to tell them "tough, you get to live on the street".