I would strongly advise that you talk to your realtor about this.
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With that said, lets take a few steps back.
The short sale process does not really begin until your offer is actually accepted by the seller. So what you do first is that your agent should be submitting all of the necessary paperwork, rpa, short sale addendum, and other relevant documents to the listing agent. Once all that is done, if the seller accepts the offer, then the short sale package will be submitted to the lender. Other documents will be submitted by the listing agent including an estimated HUD.
As for your part, the short sale lender will most likely require the additional information you described above. This helps the short sale lender confirm that this is an arms length transaction and that you are not related to the seller in any way. However it really should not be necessary to give this until your offer has been accepted by the seller.
If the offer has been accepted by the seller, then yes it is customary to provide that other information while the short sale lender considers whether to accept the offer or not.
