can a respondent's attorney request my income without me being served or ordered by the court

The question doesn't give much context. If there is an open case, then your ex is entitled to find out your financial information. If your ex is requesting documents per an agreement (like a settlement or separation agreement that you signed) then s/he may also have a right to them. If there is no open case, perhaps your ex is trying to assess whether to take you to court. Call up and ask what information they are looking for and why. Maybe you can reach an agreement without going to court (saving you time and money). Talk to a lawyer near you for more information. Good luck?