Yes, refunds are credited to your Oyster online account where you can choose to have a cheque posted to you or the balance added to your card. You can even save up your credits to use on on your season ticket!
It takes 5 days for Tfl to credit your Oyster online account.
Yes, the service will process all cards registered on one account.
You shouldn't need to do anything, the service runs on your account every 48 hours, so it can take up to two days before your refund gets processed.
When you log in to ClaimMyRefund you're automatically taken to a status summary page which tells you how many journeys have been checked and when a check was last run. In addition you will also be advised if there is an error on your account. Apart from that, relax and let the service run for you.
Yes, contactless jouney history is collected so long as your contactless card is registered with oyster online.