Is there a way to populate information from a SQL lookup to the Address Fields in Forms, or is there a way to add multiple lookup values to a text field in Laserfiche Forms?
I'm not sure you can do it with the address field without some custom JavaScript. If you make text fields for each address entry though, you can easily do a database lookup based on a value to populate the address fields. We are currently doing this with a couple of forms. It looks at the employee email address and pulls back from our HR software the employees address. See below.
Right, because each address field in Forms is composed of multiple input boxes, it's not possible to directly fill address fields with lookup rules. If you have the different parts separated out, you can do something like what Blake mentioned and then use some JavaScript to pull those values into your address field, if you want. This page of the online help has more general information about address fields. If you want an example of filling these fields with JavaScript, see my answer to this question.