Saudi New VISA Extension Policy

Hi,
      I am in Riyadh Saudi Arabia on a Business VISA , In my VISA it is mentioned like Number of Entries : "Multiple" , Validity  "90 Days" and Duration of Stay " 30 Days ". I Need Clarification on below questions :

1. Should i have to leave Saudi and enter again for every 30 days from my date of entry (without applying for any extension)  to utilize  the complete 90 days validity , (which means i can stay in Riyadh for 3 months  by doing exit&entry twice with the same VISA). Please Clarify?

2. If I am not leaving Saudi,  how many more days can i extend my stay in Saudi (within validity period) , how many days prior to my expiry of stay should i apply for extension ?

3. People staying in business VISA in Riyadh tell me that  , Once you come inside Saudi on business VISA even with 30 days stay and 30 days validity , the VISA can be extended any number of times with validity also, Is this true even after implementing  new Immigration laws, which came into existence in August 2013?

anyone please reply with clarity. I am totally confused about my Stay here .