Real-time integration with Xero, QB Desktop, MAS 200 and Freshbooks

Hello, We currently have a real-time integration with Quickbooks online. I am looking to replicate the commands currently used with Quickbooks to have a second integration with an accounting system. 1) I will need to develop the authentication for each of these systems so that it can be handed over, inserted into our code and work. 2) I will provide you with a list of all transactions that our system uses to send/receive/interface with Quickbooks and I will expect those translated to a Xero, Quickbooks desktop, MAS200 and Freshbooks format with the ease of plugging this in. 3) I will want 6 months of support with each API and the functionality built in case there are problems. 4) I will expect you to have an account with each software system that can be used for testing. It will need to work exactly how our Quickbooks integration works. 5) I will expect to get a detailed step by step document explaining the process for setting up an account in each of the accounting systems for each of integration. This is very important. If you have never done an API integration with an accounting software, please don't bother applying for this job. I will be looking at prior work done before making any decisions. Thanks Desired Skills MySQL Administration, PHP, Xero, Freshbooks, MAS200