the man known as...

[azz]

a. I talked to the man known around here as 'Tall Bobby' who is the mayor of the town.
If there is only one man known around here as 'Tall Bobby', don't we have to have a comma before 'who'?

b. I talked to the man who is the mayor of the town known around here as 'Tall Bobby'.
Do we need a comma after 'town'?

c. I was in the department known as Boyer that has a flourishing mining industry.
Do we need to replace that with 'which' and have a comma before 'which'?

d. I was in the department that has a flourishing mining industry known as Boyer.
Is the above sentence grammatically correct?

Many thanks.

[Alan]

Yes to all.