There were many creators of webnovels, and some of the more well-known ones were:
1. Battle Through the Heavens-Heavenly Silkworm Potato
2. The Peak of Martial Refinement-Momo
3 " Full Time Expert "-Butterfly Blue
Lord Snow Eagle-An Outsider
5. Douluo Continent-Tang Family's Third Young Master
These novels were all very popular works on the Internet, and their creators were all well-known figures in the industry. But these are just some examples. There are actually many other web novels that have different origins.
There's no way to really tell if it's common specifically for someone named Jojo. However, in general, reading fanfiction is a popular activity among fans of many different franchises. The Jojo series has a large and dedicated fan base, so it's likely that there are fans named Jojo who partake in reading fanfiction, but we can't say for sure how common it is without more data.
Perhaps this Jojo is interested in exploring different interpretations and stories within the Jojo universe that fans have come up with. Fanfiction often takes the existing characters, settings, etc. from the original Jojo series and creates new and unique storylines. So, this Jojo might be a big fan of the series and wants to see what other fans have imagined.
It depends. Maybe there are some telltale signs or elements that suggest it's a JoJo reference fanfic, but without specific context, it's hard to say for sure.
The JoJo manga is mainly in black and white. Colored versions exist but are not the norm. Sometimes, colored illustrations are done for promotional purposes or by fans.