You should understand the difference between a value conversion "cast"
like "(int) 3.0" that creates a new value, and a type conversion cast
that only re-interprets existing bits.

To understand the papers, you should know the term "currying":
https://en.wikipedia.org/wiki/Currying.

Answer the following questions:

1. What is the distinction between
  \cal{E}[[e]]E
and
  A |- e : \sigma
?  Explain in 2-4 sentences.
(Read "\cal{E}[[e]]E" as LaTeX code.  "\cal{E}" is the script letter E.
"[[ ]]" are double square brackets that are smashed together, in
"blackboard bold" style.)

2. What does "type safety" mean?  Why do we care?  How far do those
guarantees extend?

3. What was the most confusing part of the reading? Is there anything you still don't understand?

4. How much time did you spend on this assignment (both the reading and answering the questions, combined)?