Welcome to the forums.
Regarding the collection agencies... If you decide to settle with them, get the settlement
in writing before paying anything. Make sure the agreement states that the entire debt is being eliminated, any "past due" notations are being removed, and your credit report will reflect the payoff.
FYI, some people get a better deal by negotiating with the original creditor rather than with the collection agency. But again, get the terms in writing.