[JesterlJoker]

There are so many ways to do this

PHP код:

SetPlayerName(playerid, "[TAG]Your name"); 


or this

PHP код:

Create3DTextLabel(text[], color, Float:X, Float:Y, Float:Z, Float:DrawDistance, virtualworld, testLOS=0) 


in which you will need to create a timer to keep this on loading that it follows the player through and through which eats up memory

To call commands you can do this

PHP код:

OnPlayerCommandText(playerid, cmdtext[])
{
    if(strcmp(cmdtext, "/tag", true) == 0)
    {

    }
    return 1;
} 


I don't know much with that OnPlayerCommand thing

I use other includes
such IZCMD, ZCMD and SCMD the last is the one I use and so far what I like the there is also Y-Less's YCMD
[PHP]
CMD:tag(cmdid, playerid, params[])
{
// Your code here
return 1;
}
[PHP]
That's all the tips I could do, I will not code because it does not justify anything... Just keep reading and you'll understand