Is a married Jewish woman allowed to expose ervah in front of a goyishe man? What about uncovering her hair? Also can a married Jewish woman make a berocha with her hair uncovered?
It is permitted for a woman to uncover her hair in front of a non-Jewish man, of course where there is a legitimate reason for doing so (such as going to the hairdresser).
The same will apply for an ervah: There is less severity in exposure in front of a non-Jew, but of course this will only apply to cases of need, such as a doctor, and so on.
For reciting a berachah with uncovered hair, please see here.
There is some debate among poskim concerning going to a Jewish hairdresser (for instance), which is due to the man being obligation to avoid any hirhur, and who is liable to transgress the prohibition of velo tasuru acharei … eineichem.
For a non-Jewish hairdresser, this does not apply, and therefore there would not be any prohibition for a woman to go to a non-Jewish hairdresser.
The same applies to an ervah, provided the circumstances require it, such as a doctor or similar charge.
Having said all of this, it remains a virtue for married ladies to go to a female practitioners, but this preference is deferred by other considerations.