I've written a simple IRC bot. but I have some problems, can you please help?
#1 How to list all users on a channel?
#2 How to get if a command/message sent by an op or not? Same with halfop/voice/owner?
#3 How to get who sent the command/message (by name).

Why are you even trying to do a PHP IRC bot? Are there any other programming languages more suitable for this? Take a look at http://www.phpbots.org/