There are no specific guidelines. All you have to do is tell us what product you want to build and what functionalities you need. Anyway, we highly recommend to clearly define what exactly you plan on building, and we are here to advise and if you agree add any needed upgrade in your idea.
The same part is also covered in the contract signed between Brainxsolutions and respected clients we make sure we keep clients confidentiality the top priority.
To give you a short answer we must prepare a project scope and create a budget. We shall tell you how much of that scope can be completed within the budget and we'll be able to estimate how long will it take
We will provide end-user documentation if the clause is included in the work contract and quoted by Brainxsolutions.