Quick Internet search says that feather quills were mainly used in 600-1800 AD. After that people gradually switched to steel. In Antiquity they wrote on papyrus, presumably with reed pens or brushes. Papyrus was used for "publication", for books and perhaps for letters, not for the actual work. The work was done on wax tablets, since the Roman times, and on sand before that. Even in 18th century, paper was not cheap enough for use as "scratch paper".

The data on when pencil became common diverge by 200 years, some say in 16th century, others in 18th.

Speaking of light sources, it does not have to be animal fat. The most common lamps used all kinds of vegetable oil. These lamps of various shapes were commonly used since Paleolith till 20th century in many places. Vegetable oil is cheaper than animal fat or wax candles in most places.

Quick Internet search says that feather quills were mainly used in 600-1800 AD. After that people gradually switched to steel.

First true mathematicians (Babylonians) wrote on clay tablets. In the Greek/Roman Antiquity they wrote on papyrus, presumably with reed pens or brushes. Apparently they switched from brushes to pens in Ptolemaic Egypt, that is exactly when serious mathematics started:

https://www.brooklynmuseum.org/community/blogosphere/2010/09/22/pigments-and-inks-typically-used-on-papyrus/

Papyrus was used for "publication", for books and perhaps for letters, not for the actual work. The work was done on wax tablets, since the Roman times, and on sand before that. Even in 18th century, paper was not cheap enough for use as "scratch paper".

The data on when pencil became common diverge by 200 years, some say in 16th century, others in 18th.

Speaking of light sources, it does not have to be animal fat. The most common lamps used all kinds of vegetable oil. These lamps of various shapes were commonly used since Paleolith till 20th century in many places. In many locations, vegetable oil is cheaper than animal fat or wax candles.