man

It is not necessarily rude, but it is very informal. It's similar to calling someone 'dude'—fine with friends, but not recommended for a job interview or talking to your grandmother.

Generally, no. In Spanish slang, 'man' is specifically for males. For a woman, you would use 'la vieja' (slang) or 'la nena', depending on the region.

Yes, but with a Spanish 'a' sound. The English 'man' has a flatter 'ae' sound, while the Spanish version is a clear, short 'ah' sound, like in 'father'.