Hello, Ankit,
I do not have all the answers but I can give you some:
1. I don't have answer for this and I am not sure that Decipher offers this functionality now. Hopefully, someone else can answer this.
2. The best practice about 15 documents each time is related to the speed of processing. Let's say that one page (document can have more pages) takes 10 seconds from the point when it is received by Decipher to the point when it is available to the user for Verification. If you have a batch of 15 single page documents (or whatever combination of documents and number of pages which results in total of 15 pages) that would equal to 150 seconds before being available to the user. Now you can do your math with 1000 pages or 10.000 pages ;). So the main driver is that your users will not wait hours/days/weeks before they can work on a particular document in a batch.
The other driver would be that one batch can be processed by one user (I guess never tried multiuser approach but I will test it today). So it is also better to have more smaller batches so that users can work on it in parallel.
3. Best way to process 10K documents? Well, you did not specify whether you have any time constraint but generally speaking - create smaller batches so that users can work in parallel and it would be being processed continuously.
Regards,