Not every manga has a light novel. It really depends on the popularity and the creative decisions of the publishers and authors.
No, not all manga have light novels. Sometimes the manga story is complete in itself and doesn't need to be adapted into a different format. Also, it might not be commercially viable to produce a light novel for every manga.
Not necessarily. There are many anime that are original creations and don't have a manga counterpart.
Yes, it does. The light novel expands on the story and characters from the manga.
No. While there are many manga that have light novel adaptations, not every manga has one. Some manga are original works that stand on their own without a corresponding light novel.
"My Manga Artist Guide" was a light novel written by the author, Xiao Xiaoyu. It was a fantasy novel, not a manga novel from "She Comes From The Deep Sea." However, if you want to know more about novels related to the deep sea, I have two recommendations here: "Lost Love in the Ocean" and "Children of the Sirens." I hope you like this fairy's recommendation. Muah ~😗
No. Manga are complete art forms on their own. They don't need a light novel to be valid or popular. For instance, many classic manga have thrived without any light novel adaptation.
I'm not sure. You might have to do some digging on dedicated manga and novel forums to find out.
Yes, it does. The anime Free is based on a manga.
Yes, it does. The anime is often based on a manga source.
It's hard to say. Sometimes daemons from certain franchises have manga adaptations, but it varies. You could try doing a search on popular manga platforms or asking in relevant forums for a definite answer.
Not that I know of. I haven't come across a manga specifically related to free swimming.