If employee is fired, & employer dissolves yrs. later & opens 2 separate firms (the 2 partners had dispute), are his evaluations discarded ?

If you were fired years ago, it's possible that your evaluations were shredded a long time ago.

Companies are becoming more savvy with document retention and no longer keeping items "just because".  If you kept it for the legal requirement which is usually 7 years for pay data and 3 years for employment information, many companies don't want the records longer than that.  If you don't have the documents, you can't get in trouble for what they say. 

Yes.  however, even if they were not, no employer is going to disclose those to someone screening job candidates.  the most they would do is confirm your start date, end date, and possibly your rehire eligibility (and being ineligible for rehire isn't necessarily a bad sign).

probably...................

Maybe.  No one here knows what happened to your evaluations.