Declarations and Initializations - General Questions

What is the range of a signed char on typical systems?

What will be the output of the program?

#include <stdio.h>

int main(void) {
    char c = 'A' + 1;
    printf("%c %d\n", c, c);
    return 0;
}

What will be the output of the program?

#include <stdio.h>

int main(void) {
    unsigned int u = 10;
    int s = -3;
    printf("%d\n", u + s > 5);
    return 0;
}

What will be the output of the program?

#include <stdio.h>

int main(void) {
    int a[4] = {0};
    printf("%d %d\n", a[0], a[3]);
    return 0;
}

Which variable is stored in a CPU register if possible?