Recursion is within the scope of the midterm.
Data representation is not within the scope of the midterm. We're just doing that now. It will be within the scope of the final exam. We're now continuing with some further numerical stuff which also is not within the scope of the midterm.
You do not need to know particular sorting or searching algorithms, but you should be able to deal with a description of one in fairly short order. You would not be asked to code one of them from scratch; that's too hard for a midterm question at this point. You could be asked, for example, to write code which swaps the values of the variables 'x' and 'y'... You could be supplied with a sorting algorithm, or some C sorting code, and asked a question about it... same for searching...
Files are indeed within the scope of the midterm (fopen, fprintf, fgets, etc).
The only C preprocessor material you need to know for the midterm is the inclusion of system .h files (e.g. #include <stdio.h>). That is, no #define, #ifdef, etc.
Structs and typedef are not on the midterm. Command-line arguments (argv) is not on the midterm.
There is a discussion of textbook coverage, especially relating to the second midterm.