[Dayrion]

Hey. I'll try to answer.

Код:

First of all, how would I be able to create a rcon command which will be used to promote and demote admins?

You use IsPlayerAdmin(playerid), which allow only player connected with RCON to use your commande.

PHP код:

if(IsPlayerAdmin(playerid)) 


For your second question, I recommende to you to create a variable with different level, not with a boolean.
THere is an example because my english is pretty bad:

PHP код:

#define     PLAYER    0
#define     MODO     1
#define     GMODO     2
#define     ADMIN     3
CMD:goto(playerid, params[])
{
    if(pAccount[playerid][pAdmin] < ADMIN) return 1;
// pAdmin is a integer which is storing admin lvl of the player even if the player is not an admin.
    new target;
    if(sscanf(params, "u", target)) return SCM(playerid, LBLUE, "/goto [playerid/name]");
    if(!IsPlayerConnected(target)) 
        return ErrorMsg(playerid, "This player isn't connected.");
    new Float:x,
        Float:y,
        Float:z;
    GetPlayerPos(target, x, y, z);
    SetPlayerPos(playerid, x+1, y+1, z);
    SetPlayerInterior(playerid, GetPlayerInterior(target));
    SetPlayerVirtualWorld(playerid, GetPlayerVirtualWorld(target));
    return 1;
}