1. You were not expected to get this. I like to consider the clause as an interjection because it lies within (between) the "My" and the rest of what he said. If you considered the "he said" as the main S/V/C pattern, with what he said as a subordinate clause, the direct object of "said," you are doing well.

2. There are several options for explaining the clauses in this sentence. In addition to what I have above, you could, as I did in the preceding note, consider "the dean answered thoughtfully" as an interjection, with "Let me see" and "I'd say about one in a hundred" as two main clauses joined by a comma-splice. "Let me see," however, is idiomatic and the equivalent of "Hmmmm." Thus the "Let me see" clause could be considered as an interjection within the "I'd say..." clause.
     Note: If all these options confuse and frustrate you, forget them and move on to another exercise. You can always come back to these after you have strengthened you basic concept of clauses.