How to automate digital signing PDF Files in batch

Question

I am trying to find a way to automate as much as possible the placing of a digital signature on a set of PDF documents.  We have Adobe Acrobat Pro 8.1 and the machine has MS Office 2003 with Vista Business.  Here's a scenario:  A set of documents exist in a TO-BE-SIGNED folder, each unsigned.  The user uses MS Access 2003 form with a button with VBA code to open and show the first document in the folder.  The AcroExch.App, AcroExch.AVDoc, and AcroApp.Show APIs are used to do this.  I found code on the internet to do that.  Rather than having my client now have to go through all the manual steps to place a digital signature on the document, I want to streamline it to a single click if possible.  Right now he has to click Advanced > Sign and Certify > Place Signature > then click and drag > then enter his password > then click sign > then save and close the doc.  Can all this be automated?  An added bonus would be automatically saving or moving the signed doc to a different folder when it is signed.
I have created a stamp that allows me to add a stamp with just two clicks.  Can such be done to add a digital signature?  Is it possible to add a button to the toolbar to do this?  Can it be done in Access VBA using some Acrobat API calls?  Another feature I want to include is moving quickly from one document to the next in the TO-BE-SIGNED folder.  Like the arrow buttons take you from page to page, can a button be added to the Acrobat toolbar to take you from doc to doc in a particular folder?  Or can that be done using VBA and some Acrobat API calls?  To maintain the security of the password protection and yet cut down on clicks and keystrokes, I would like to input the password just once at the beginning of the session and have it remembered or applied to all the docs that get signed as long as that session is open.
I've found some software that purports to do much of the above, but they are all very expensive and assume a big business with big bucks.  If anyone knows of inexpensive software that will REALLY do this, I'm open to that as well, though I'd like to control the process myself if possible.  I consider myself a beginner with Acrobat and using API calls and would appreciate any help anyone can give.  Is the above clear and even possible?
PS:  I'm new to this site and using SDK.  I posted this under Security (thinking digital signatures) and was asked to post it here, which I'm glad to do.
Thanks much!

Answer 1

Our workflow is such that on infrequent occasions, we have a digitally signed PDF file and the doctor wants to append a scanned note to it.  In the past, we could do this, but not now.  In the past, when we added the scanned doc, we received a message saying that the doc is already signed and asking if we want to overrwrite the doc.  If we respond Yes, then Acrobat would allow it and the signature would indicate that the original part of the document was not modified, but that something had been changed--namely, a doc had been appended.  The signature indicated that something had changed since it was added, but it still allowed the append.  The signature would have an exclamation point in a yellow triangle indicating the doc had been updated since signed.  For our purposes, that was okay because we know what the change is based on the original doc and we know what is appended.  Now, however, we cannot append at all.  The only thing that is different that I know of is that the doc was signed with software that is not Adobe Acrobat, even though the other software uses an Adobe Acrobat self-created digital signature.
    I hope I've explained that clearly enough.
Thanks for your help.