I noticed in the faiths info section that monks are listed as worshippers of savras, what order would these monks belong to?

Or are these members of the "old order"?

Old Order Monks are specifically devoted to a particular belief system set around a dogma of a likely long dead god, and is representative of a specific order. They (as a group) have no current devotion to any living diety's dogma.

Monks of Savras, as uber-rare as they likely are, will follow and adhere to the dogma of Savras and mold themselves around that.

Is there any official info, on what the order is called, if there are any multiclass availabilities (like other orders), probably wizard?

https://efupw.com/efu1-forum/topic/28/283/monk/index.html

Try here, it's probably the most you will find on many of the orders that is canon information. It's just that a lot of the orders are mentioned in passing in an obscure book somewhere, and so are put into the canon liturature.