What's the best way to reverse lat lang data collectd through forms and add the resulting addresses as an additional column to the database?

@mika with reverse geocoding you mean “translating” the GPS coordinates to addresses on the server?
In that case I think your initial post is one (or the) way to do it.
On the device directly I see that in Enketo you can search for an address to help you select a geopoint, but I don’t think you can take a geopoint and then save the address too in an extra column.

Also check this info