Quickbook API integration with salesforce.

Simple one way opportunity to invoice sync in QB, Create company if not already in QB Need to create a trigger on opportunity that will sync create/update invoice in quickbooks using standard API. 1) Create a custom settings to store information needed to connect with oAuth 2.0 between salesforce and quickbooks. // Proper document should be shared for the steps required to aquire that information from both salesforce and quickbooks. 2) Create a class for authenticating with quickbooks api. 3) Create a class for invoice creating and update. 4) Create a class for company(sf account) creation in quickbook. 5) Create a trigger on opportunity create that will create company if not in quickbooks and then create a invoice for that company. 6) Write test classes for all of above. Acceptance criteria. Demo over video call in which we create a developer account for both sf and quickbooks. and copy code and create new custom settings in new sf account and create a account and opportunity. Invoice and customer should be created in QB create a dev sf account and dev quickbook. freelancer to document the whole process from start to end If we are going to do it for a new sf and new quickbook account how to do. Please answer these along with your proposal. 1) How long it will take? 2) Do you already have experience with QB API's?