Her opponents could be the Separatist forces. Umbara was a planet involved in the Clone Wars, so it's likely that battle droids and their commanders would be her foes. They would be trying to gain control of Umbara's resources or strategic locations.
In some versions, it could be a former ally who has been corrupted. This character, once on Ahsoka's side, has now turned against her due to some external influence or personal greed. Their knowledge of Ahsoka's strengths and weaknesses would make them a formidable opponent, and they could be the one to cause her death.
Ahsoka can be developed by showing her growing understanding of Anakin and Padme's relationship. For example, she could start off being a bit naive about love and then gradually realize the depth of their connection. Also, her skills in the Force could be enhanced through her experiences with them. Maybe she has to face a powerful enemy alone while protecting Anakin and Padme, and this forces her to dig deeper into her Force abilities.
Naruto would probably be very curious about Ahsoka's Jedi powers. He might constantly ask her to show him how her lightsaber works. Ahsoka, on the other hand, would be interested in Naruto's ninjutsu and his ability to use chakra in different ways. They would likely start off with a bit of friendly competition, showing off their skills to each other.
Ahsoka and Barriss could be on a mission together on a far - flung planet. During this mission, they face many challenges, like dealing with local hostile forces and difficult terrains. As they struggle through these difficulties, they grow to understand and respect each other more deeply. For example, Barriss might use her medical skills to heal Ahsoka when she gets injured, and Ahsoka could use her combat skills to protect Barriss from danger.
Well, determining Ahsoka's age in the novel can be a bit tricky. It often depends on the timeline and events of that particular story. Sometimes it's explicitly mentioned, but other times you might have to do some detective work within the narrative to figure it out.
The Ahsoka novel is indeed canon. It fits within the established framework and narrative of the Star Wars universe and contributes to the overall lore.