I have a doubt: which is the object of chtít, nominative or accusative?
It is accusative, as the direct object of the verb. Co has the same form in both the nominative and accusative case.
Are muži and mužové interchangeable?
Muži is much more common, mužové sounds strange in most non-poetic contexts. It is a complex topic with many subtleties for different words https://prirucka.ujc.cas.cz/?id=226