Perhaps he could add an optional transform to the binding string, so you could append :JS(c_to_f.js) to what you currently supply, and write your own conversion in a simple line of JavaScript. Lots of other bindings do that sort of thing. More capability down the road by empowering users to transform values themselves.
Not that I’m aware of. It might make sense to add a new Map element to sitemaps:
Map [item=<itemname>]
where <itemname> could refer to a Location or a Group item. In the case of a Group item, all Location items in the group would be shown on the same map, with the <itemname>s’ labels. Just a thought. For now, I’m not aware of a non-very-complicated way.
My current setup just renders a Group of items and the Location item is in that group, so there is no specific sitemap entry.