Can I create and sell reading guides for novels on teacher resource sites such as Teacher Pay Teacher without getting into copyright issues. I would, of course credit, the author for all of the book content, and wouldn’t include any images or large chunks of text. Maybe a cited sentence here or there at most. I would really just be selling the questions I write based on the novel in the organizational structure I create. I wouldn't be adding to or building off of their work, just providing questions teachers could use with the book. (They would still need a copy of the book to use the guide.)
If a work is protected by copyright, creating a work with comments on, analyzes, or criticizes it is, under US law, usually a fair use of the source work. If the new work contains "excessive" quotation, then it may be held not to be fair use. The usual "reading guide" is a fair use of the book it is about. But what is and is not fair use is very fact-dependent, and is ultimately determined on a case-by-case basis.
Crediting the author for quotes can help the case for fair use somewhat, but it does not automatically decide then issue.
If the guide could be used as a substitute for then original novel, that would weigh against fair use rather strongly.
If the guide is a fair use, selling it would not normally change that.
Note, "fair use" is a specifically US legal concept. The issue would be covered by other legal concepts in other countries, but a similar result would often occur.
Use of the title or the names of characters would not infringe any trademarks on those, if they were trademarked, provided it is made clear that the guide ism not authorized, sponsored or approved by the author or publisher of the novel. Titles and names are never protected by copyright.
Public Domain Works
If the novel is in the public domain, whether because the copyright has expired, or for any other reason, anyone may use as much of it as s/he pleases, because there is no copyright. In that case one could freely quote half then novel if one choose to, legally. Whether that would make a good guide is another question.