It is a nice idea, but it does not work at least not in EU.
It is also a nice idea for personal freedom, but not for the benefit of the society.
Minimum wage is a way much better thing.
For a)
The EU has the property, that any citizen has the freedom to choose freely his work place and to choose freely his living place. People are using it and this is good for one and bad for others.
For example here in Germany, we have many people from Poland, Hungary, and other such countries working in jobs for cheap, at least cheaper than a German works for. Jobs are like health care system, construction work, butcher, and even in Amazon Fulfillment centers and alike. For them it is still a lot of money, because their and their families living place are their home countries. It is way cheaper to live in those countries than here in Germany. (I think the same is true for the Netherlands, Belgium and others.) So those people live here in Germany for cheap, because they consume here in Germany few to none services and goods. They bring their goods from their home countries with them. So that they can save money for the family support at home. That leads to the situation, that the money is removed from the circulation within Germany. Little to few services consumed means, no jobs for others, means also no taxes for the country.
That is not changed with BI. It is even more, local people (or people who decided to have their living place in that country) will benefit from BI and decide not to work for that low income. That is not a problem for the companies, because we have lots of those other people, who will work for that money, which will not qualified for BI. So basically, with BI you will introduce an even lower class/society.
Versus with required minimum wage the country, the society can set that to a level, which supports to live in that country. So that people are willing to work for that income. That means, that the money will no be removed from the country by people from abroad. The money will be used within the country to consume services and goods and as such will support other jobs as well. That will lead to an healthy economy.
For b)
BI is not for people with disabilities. Do you really think, that people with disabilities should have the same amount of money? People with disabilities have way higher costs of living. They need special support in terms of (medical) device, re-fitted living space, re-fitted mobility requirements, and much more. So that people with disabilities have an equal quality of living, they need more support. But all ideas, I have seen so far, consider also the budget dedicated to people with disabilities as budgets to be usable for BI. That is like a kick in the ass to the people with disabilities.