Tier-2 visa

Hi all,

I am changing job. My new employer has Tier-2 license (as did my old employer). But during the interview stage they said they currently hold 1 license and they are sponsoring a Chinese person on that already.
My questions are:
1. How many people can the employer sponsor under their existing license?
2. What is the procedure to extend the number of sponsorship licenses and how long does this take?

Thanks in advace

Thisisme