Directing a quote to a prospect
Yes it is possible to address a quote to both a prospect and a customer. This works exactly the same way and no changes to the document template are required for your quote.
As soon as you start working with prospects, you will see that for a quote you can choose to either search for a "customer" or a "prospect" or suddenly create a new customer or prospect.
What if that quote is then approved?
If that quote is approved, the prospect will automatically be converted (converted) to a full-fledged customer sheet. This is done with data retention.