Welcome to the Community, @info747.
You can modify the default message for invoices to include your bank details in QuickBooks Online. However, it's not recommended to add this type of information for the safety of your banking information.
In case you want to push through the process, here are the steps:
For your second question, yes, you can let your customers pay by clicking the Pay now button from the invoice you're sending to them.
I recommend you visit the Create an invoice your customer can pay online article for future reference. It contains information about how you can accept payments online.
I want to make sure this is taken care of for you. If you have any other concerns, post a comment below. I’ll pop right back in to assist further. Have a good one.