All the programs in the text illustrate good style. Good style should be almost automatic; you don't even have to think about it, just do it whenever you type.
Ignore "warnings" from the compiler, they will not effect the behaviour of the program. Warnings are mostly for very nit-picking minor details that usually are to make the program ultra-conformant to the language standard (for commercial software you would fix the warning problems). Only "errors" prevent the program from being compiled and thus executed. Warnings do not prevent the execution of the program.
When you compile and get a long list of errors ignore all but the first one. Try to fix it, the following errors could just be a result of the first one, so they might not be real errors. Don't worry about the number of errors when you reducing errors.
The major part of the grade/score you receive for the homeworks is for a correctly working program; that does everything required of it as specified in the assignment, that does so without error. You need to thoroughly test the program to make sure all possible logical paths thru the code work correctly. E.g. lab 1: test all the error handling and also check a few scenarios (check against hand computed values, don't believe what your program tells you, it could be in error and thus "lying").
It's better to turn in an incomplete program with errors than to not submit anything, which counts as zero.