I believe the lack of responses is again attributed to your lack of specificity. Your optimal solution will always depend on the way your current system is set up, but I will try to give some pointers.
Parsing messages is best done with a tokenizer. I made my own, but there should be libraries in your language you can use. When the message is isolated, you simply match the message to your command structure. If the structure has complex parameters (e.g. !addcom -ul=mod !hello hello @user@!) then simple string matching might need to be replaced by regular expressions.
Grabbing users from messages are also done with tokenizers, and regular expressions in regard to JOIN/PART.
Channel data is loaded through the API, there is a lot of documentation and discussions on this in this forum. For parsing twitchnotify messages, I suggest trying out @night’s regular expression.