use of jquery mobile in buildin a mobile site

Please, am planning to bulid a mobile site for all platform that can accomodates more than 100,000 users in future using jquery mobile, php(PDO) and mysql database. my question is

1: is peer to peer chat application possible with jquery mobile.

2: For chat and message processing, can mysql database be able to handle that if limit is set in query statement without the database being crashed. or is there any alternative via any reliable 100% free push for message and chat sending and recieving.

3: Is online and offline message sound, alert and phone vibration possible with Jquery Mobile.

4: What could be the best way to handle this scenario

Thank You.