Re: fast forward.
"The tax bands and rates will change so that for instance someone like me in a normal job doesn't get any benefit for the UBI even though I still get it (heck might even lose a little bit in tax)."
If you rely on extra tax on high incomes or large corporations to make it work, take a look around you. If X hours effort expended on rearranging tax affairs brings in more money than if it were expended on earning then that's what will happen and your hoped for taxation to fund it will be elusive. Should you manage to lose the benefits bureaucracy - IMV unlikely - you'll probably just redeploy it trying to collect taxes.
You might be able to find a new tax base in terms of taxing the output of machines on the basis that these are going to take over employment. Employers will just respond by continuing to employ low paid workers (will there be any justification for a NMW/LW with UBI?) and lock in low productivity still further.