I am
very proficient in PHP and MYSQL/MYSQLI, as are a number of the guys here. Are you looking for a guide on the SQL statements? I would say a predominant number of the SQL statements are pretty cut and dry... INSERT INTO, SELECT * FROM, etc.
You're looking to do db backups... are you looking to schedule it from crontab? Or execute a PHP script? Your answer would dramatically modify the direction I point you.
I think you'll find the
MYSQL Manual helpful. And I have always been a fan of the
O'Reilly MYSQL Books, many of which are available online (downloadable too).