I will answer your questions here, but cannot create documents for you to use. Also, I cannot tell you whether to respond to particular questions or requests, in some cases you may have legal defenses to certain questions. I cannot go over this intricate area of law in this forum as it is fact specific and I cannot state that you must respond to all of these questions. Now, generally,
You have been served discovery and have thirty days to respond. You can ask for more time to respond, either send a letter to the attorney asking for more time, get them to agree, or file a motion with the court. If you do not answer they will file a motion to compel and sock you with costs and fees for failing to respond.
Yes, you have exactly the same rights. AND, you can send out subpoenas, call witnesses and engage in legal discovery to discover facts you want. Think about copying their set changing petioner to respondent
(or the term in your court) and using it after it is modified.
You will want all of the information possible before mediation. Now, you are right, there may be an order requiring mediation before discovery. You will need to check the court's order. If there is such an order, you will want to write the other attorney, remind him of the order, and state you will answer appropriately if mediation is unsuccessful.