C linked list manipulations

I have to insert, delete, print all, and print specific members of a linked list.

        typedef struct tnode
                {
                int wayptnum;
                double x;
                double y;
                double heading;
                double distance;
                struct tnode *next;
                }gpsnode;

That is my link list struct definition.  I want to include a next that indicates the location of the next record.  Why does this have to be so elaborate?  Since the next entry is a pointer - doesn't that mean it is just an integer value of a memory location.  So, why not have int next instead?

        while ( fscan(fileptr,"%c%i%d%d",cmd,waypt,x,y) != EOF )
                {
                switch (cmd)
                        {
                        case 'a': insert(gpsnode **head, gpsnode data);
                        case 'P': prntall(gpsnode **head);
                        case 'p': prnt(gpsnode **head, gpsnode data);
                        case 'd': delte(gpsnode **head, gpsnode data);
                        default: printf("%c",cmd," was not a valid option.");
                        }

This is my routine for dealing with an incoming command from a file.  The compiler gives a parse error.

So, what's wrong with case 'a': insert(gpsnode **head, gpsnode data); ?

and why am I passing a pointer to a pointer?  Why not just pass the address of the head of the linked list?

Do I need more to pass more arguments?  Am I legally passing arguments that are legal?  As I see it, I only need to pass the start of the list plus the data that needs to be printed, deleted, or inserted.

After main, I plugged in some function as placeholders.  

        return(0);
}

insert(gpsnode **head, gpsnode data)
        {
        int dummy;
        };

I get a parse error.  Why is the syntax illegal?

Thanks.