The oil will be a linament like Bigeloil, or a version of it considering the context.

http://www.absorbine.com/products/muscle-care/bigeloil-liniment

It's to help circulation after a race, likely the same as a human having a rub down or bath/shower/scrub down after a big exertion or event.

Gypsum powder - one of its many uses was for medicinal splints.

Can't come up with anything for the yellow oil.

This is still done in camel racing in the United Arab Emirates. The author of this article was interviewed on NPR and talks about the application of the oil or powder that was spiritual in nature. That part doesn't appear to have made it in the article but it was definitely discussed in the interview.