There's a possibility that you may have to use a different name for the file. I put the network and channel information into the file name, so that mIRC wouldn't recognize the windows reserved word of IP, although, that might not have worked. Try changing the IP in the file name to something else.
1) Leave the 2. That parameter is being used to tell the protect line what format to protect. For other options see /help $mask
2) I don't know why you can't find it, unless you're using a help file that is out of date, or you're entering the word incorrectly. I'm using the help file from mIRC 6.21 and here's the spelling using capitals, so that the letters are easier to distinguish. /help /UPDATENL 3) If neither of those posts work for you, then it makes little sense for me to review them and recommend one.