Are you referring to year-end bumps or a mid-year/early-start bump?
In general, you have to play at least 3 matches in a USTA year to have your rating change, so if you are referring to year-end, I don't believe playing just 2 matches would be enough. This player would stay a 4.5C AFAIK.
To the second question, if you play enough (3 or more) men's matches, your rating will be based on only those and mixed matches won't count towards the year-end rating.