I need some assistance on a QuickBooks Online - BrainTree integration.

Some history -

*I have an active QBO, but used journal entries to summarize customer information monthly.

*I have an active BrainTree account that integrates with microsoft D365 for customer invoicing and payment processing.

*We manually enter customer credit card info for new customers into D365.

I am moving to QBO and removing D365 so invoicing can be done via QBO and credit card processing can be done via BrainTree.

My most immediate questions are -

1) what steps are needed so I can see where in QBO you would enter a customer credit card data for new customers?

2) Do you need a 3rd party app to make the integration easier (PayTraqer, etc) between the two systems? 

3) Does current BrainTree cc data integrate back into QBO?

Any help is appreciated.

Dan