Piwigo is my photo-gallery. It needs mysql and phpMyBackupPro to backup. Also php-exifs to manage photos metadata.
Then follow the piwigo documentation. It's not always easy to find, but don't forget the community is very active and the developpers anwser to users questions, so the answers are very accurate.
On modern piwigo versions, the update is automated. When an update is available, the admin is informed the next time he opens piwigo in admin mode (he can also subscribe piwigo mailing list as usual), and a click of a mouse make the update. It's pretty harmless is done often. If not may be one have to think a lot before.
Same for most plugins, they can be chosen, installed and updated from inside piwigo. Very handy.
When moving piwigo, copying the complete folder and the data base makes the move. Php error may appear in case of php change. Search on the piwigo forums should gives the solution.
Data base name and parameters are in piwigo/local/database.inc.php, including base name so it's possible to change base there.
Updating database to use external repository
Code: update piwigo_images set path = replace(path, './upload', 'http://galerie2.com/upload') ;