I-140 is your employer's petition. So they will have to provide documentation support which includes and is not limited to Ability to pay, financial documents related to your company etc. In addition to company's documents, your attorney might/will ask you for probably a resume, copies of your work experience letters, educational evaluation, latest paystubs, W-2s etc.
For 485, you will have to provide copies of your Birth Certificate, you will also need to do Medicals from a CIS approved physician.
You will have to fill up one 485 application for you (as primary applicant) and similar applicatons for your family members (spouse, kids etc).
Generally, attornies who are processing your case will ask for details which will include the above things + others as deemed fit to your case.
