1. People at the party were attired in a variety of styles. (as a verb, similar to "dressed", "clothed") The attires of traditional peoples are interesting. (as a noun, similar to "dress", "outfit", "costume") 2. I don't see anything wrong. "attire" is a general term for how one is dressed, in a factual sense without any special nuance. It is a rather academic word used mostly in writing. In daily life, clothes, dress, and outfit are much more common.

If this is for a museum display I would suggest using 'costume.' You might be able to use 'clothing" or 'clothes' in some of the displays. 'Attire' is not the appropriate word in #2.