Some of these concerns are overstated.

The UBI should be taxed like any other income. It's already a drop in the bucket for high earners; it will be even less so if taxed at the top rate.

Funding is easy. Just print the money and see if it doesn't bring forth sufficient taxable production to cover the cost. Most of the UBI money will be spent over and over again, with Uncle Sam picking up a slice as income on wages and profits.

The UBI should be subsistence level income. Few people will prefer to live on it if they can keep all of their actual earnings on top of it.

Big Brother is coming or he isn't. A UBI will have nothing to do with it. The UBI should be implemented through the income tax system, as a reduction in withholding or as a refundable credit. The math is simple. Pretend everyone's income is increased by the amount of the UBI, and then give everyone a credit equal to the UBI. For most people, no cash will need to change hands. The UBI will show up in their paychecks as less withholding.