Bot framework to work with LUIS intent & match intent & pro-active dialog

I've built a bot using LUIS framework which works fine. while working on it came through few points as mentioned below

1. After connecting with LUIS intent; bot is unable to check with regex intents like

   for ex dialog.matches('^helpdesk/i',function()) which i'm trying to setup

var dialog = new builder.IntentDialog({ recognizers: [recognizer] });

1. How to proactively send greetings message to user before inititates conversation like i would send prompt of choices to user which user can select. If nothing is fitting to that requirement i want LUIS to work and understand on that
2. How to know the logged in user context in Skype for Business channel
3. cards are not working in skype for business

via Shujaath Khan