Are you allowed to go to the bathroom to urinate with your Tefillin on? Discussed in ש״ע :Perek מ״ג and all relevant comments in Mishna Brura.
Permitted assuming everything stays clean.
Fun fact: Rabbi Shmuel Aurbach didn’t take off his tefillin when using the bathroom.
Was that,I assume ONLY for מי רגלים.
Yes