C

Question 1

Variable Argument Lists:

• signature
• usage
• caveats

Answer 1

signature: int foo(type bar, ...)
The ... indicates variable argument list. At least one type is required to preceed (as its used with stack magic to make this work)
usage: 
int foo(const char* format, ...) {
va_list list; // declare the va type
va_start(list, format); // pass in va_list and preceeding type, this initializes things
type a = va_arg(list, type); // grabs the next item casting to desired type
caveats: you have to know how many arguments there will be. It uses stack magic.
#include

Question 2

char, short, long, long long

int can be short or long

Answer 2

8bits, 16bits, 32bits, 64bits

int is typically 32bits

Question 3

VLA (Variable Length Array)

Answer 3

As of C99
Array sized at runtime, via variable arguments, allocated on the stack.
int array[x][y];