1. Personal opinion
The point of a summary is to sum up the story, so there is no need for personal opinion. If you wanted to provide an opinion, then you should do a book review.
2. Slept like a log
In this expert, we are comparing with like, so it can be considered a simile. Also, the phrase “slept like a log” is an idiom.
3. To come to a conclusion based on provided information
You aren’t developing the personality (the author does that), and a wild guess isn’t an inference. The mental image can come from an inference, but that’s not the meaning. The definition of an inference to to make a guess based on information, so it isn’t “wild.”