Hello Shansy,
Welcome to the World of the Kaskara. The best way to learn about the type is to read forum entries and discussions on the subject by searching on the EAA forum. Over the years the forum members have discussed most aspects of the type. Their knowledge and collected examples cover most all types and variations.
There are no books on the kaskara. However, there are several pdf articles and essays available on-line that you would be well served to print them out for ready reference.
Reed's Kaskara of Northern Darfur, Sudan, 1987 is excellent.
file:///Users/edhunley/Downloads/Kaskara%20from%20Northern%20Darfur%20(2)_Kwon%20Co mpressed%20(6).pdf
EAA's Geographical Index has some seminal texts. First was Lee Jones's "Kaskara-Broadswords of Sudanic Africa". Also, see Julie Anderson's piece of Ali Dinar's swords. I wrote a couple linked therein. Also, one on cross-guards has been converted to .pdf by Lee. and the third, on Silver Dress is in press. It's basic thread is available via an EAA search.
http://vikingsword.com/ethsword/hunl...ara_guards.pdf
Iain Norman is the expert on the Takouba. While this sword is from a different ethnic base, they often share common blades, marks and other attributes. He has also written on the Kaskara. Check out his Essays. They are outstanding.
Your third sword is Thuluth decorated and with a characteristic cross-guard. Lots of info is available via Forum threads.
Good luck in digesting all this material. Kaskara is within a pretty broad field that got its cachet via Sudanese history mostly the Mahdist Revolution 1882-1885 and the British Reconquest 1998. Actually, the history places the sword within its ethnographic context.
Best regards,
Ed Hunley