Updating all footprints on a board, including the texts

Just a general remark: the nightly builds between 5.0 and 5.1 are project compatible with 5.0 and usually quite stable, there may be some crashes but not much. Therefore it’s pretty safe to handle a 5.0 project with current nightly builds. This will probably change radically after 5.1 release. See Is it a good idea to use a nightly build version?.