The correct answer is is, are.

To choose the correct verbs for the blanks, we need to apply the rules of subject-verb agreement for both sentences.

Step 1: Analyze the first sentence
Sentence: "This book, including all its chapters, _____ interesting."
The main subject of this sentence is "This book", which is singular. The phrase "including all its chapters" is a prepositional phrase/parenthetical modifier and does not alter the number of the main subject.
Since the subject "This book" is singular, it requires a singular verb: is.

Step 2: Analyze the second sentence
Sentence: "The students as well as instructor ______ in agreement about it."
When two nouns are connected by phrases like "as well as", "together with", or "along with", the verb agrees with the first subject.
Here, the first subject is "The students", which is plural. Therefore, it requires a plural verb: are.

Combining both correct verbs gives: is, are.