They don’t need to read you your rights for a field sobriety test. I believe every state has laws that make consent a condition of the drivers license and establish that the tests aren’t self incrimination.

They should have read you your rights but if they didn’t question you after arrest it’s probably academic, since failure to do so would mean the answers you didn’t give to the questions they didn’t ask were inadmissible.

A dwi doesn’t require alcohol. They could just say you were on “something”. It’s a catchall for not being in a fit state to drive.

Anything anyone says here is pointless. You need to talk to a lawyer.