Hey fgdonovan,
MethodCRM is the perfect solution for the needs you have listed in the post above.
We do not recommend the storage of any credit card information within Method's database as it is not PCI Compliant. That being said, we are currently working on releasing credit card authorization tokens which will enable us to request tokens from merchants and process credit cards stored within merchant databases without handling any credit card information directly in Method. We hope to have this released over the next few months.
I would recommend you store your customer credit card information in QBO (Quickbooks Online) which can be referenced by MethodCRM (Using QuickBooks Merchant Services).
With QuickBooks Merchant Services you can easily manage recurring billing; however, you can not automate billing using Method.
For occasional customers, who do not require recurring charges, Method enables you to create a custom payment portal which will allow users to login, and pay their outstanding invoices on-demand.
I hope this helps,
Nelson