Why are my "<br />" tags getting converted to "<br />"?
Your problem is with
$("#venueaddress").text(venueaddress2);
you should use
$("#venueaddress").html(venueaddress2);
Text will encode any html character and will display it in span as encoded, html will not.
<br /> == <br /> You just need to Decode the output to get back the original HTML.
Use javascript unescape function
Presumably because when you are inserting it into the DOM, you are inserting it as text and not as HTML.
Since you haven't show the code you are using to do that, it is hard to say for sure, or to say what the best way to change it so it expects HTML would be.