After /refreshfilelist the file should be visible for /find if the file is in the levels folder. With the latest npcserver update you need to give "(npcserver)" read and write rights to the file though.
One problem with watching files can be that the server created the file in a different folder than you expect, would need to know the server name and script name to check the problem.
Player.chat can be read and written to, but is not a variable itself (it's just like a pair of functions for reading and writing), that's why you cannot use it for loadstring and similar. Do something like
PHP Code:
temp.var.loadstring(filename);
player.chat = temp.var;