Every payment generates a PDF invoice available in Settings → Billing → Invoices, and a copy is emailed to your billing contact.
Go to Settings → Billing → Invoices for a list of every past charge with a PDF download. Invoices are also emailed to the billing contact on the day the charge succeeds.
Settings → Billing → Invoices.
Yes — Settings → Billing → Company Details.
Same screen, Billing Contact field.