You can start from the chapter where the anime ended. Usually, there are online forums or manga communities that can give you specific chapter recommendations.
Mostly, yes. The Gate anime does follow the novel to a large extent. The main storyline about the gate opening to a fantasy world and the military's actions in that world are similar. However, like many adaptations, there are some minor differences in pacing and character development. For example, some side stories or details in the novel might be condensed or omitted in the anime for the sake of fitting within the time constraints of the episodes. But overall, fans of the novel will find the anime to be a fairly faithful adaptation.
The Gate anime does cover the novels to a large extent. It takes the main plot elements from the novels, such as the opening of the gate to a fantasy world and the military's response. But there are some minor sub - plots and character developments in the novels that might not be fully explored in the anime due to time constraints or other reasons. Overall, if you've read the novels, you'll find the anime quite familiar, but it also has its own take on the story in some parts.
There were many anime works similar to Gate:
1. Steins;Gate
2. Attack on Titan
3. Tokyo Ghoul
4. The Walking Dead
5 Demon Slayer
A Certain Magical Index
7《Fate/stay night》(Fate/Zero)
8 Steins;Gate 0
9 Sword Art Online
Chapter 10: Danganronpa
These anime works had unique settings and plots that were worth watching.
The sealed male and female Demon Gates were part of the plot of Demon's Mystery. The story was about two different demons, the male and female Demon Gates, who were caught in a bitter battle for different reasons. In the end, they decided to be sealed together to prevent them from posing a greater threat to the world. In the anime, the relationship between the male and female Demon Gates was quite special. They were lovers, but they were sealed together by other forces and could not be separated.
The Gate anime tries to cover the novels, but it's not a one-to-one match. Some elements might be emphasized or de-emphasized for better visual storytelling. However, fans have varying opinions on how well it does this.
I don't know the specific author of a particular 'Hells Angels Novel' without more context. There could be multiple novels about them written by different authors.