Switching from fulltime employment to freelancing

Hello.

I will quit my current job soon and am considering to do some freelancing in the future.  I have been working as consultant in the telecom/IT sector.
I read from the internet that I may need to fill in a form, “Fragebogen zur steuerlichen Erfassung”, to let Finanzamt know about my plan to become a freelancer.

My questions are:
1)  will I lose my current Steuernummer after I quit my current job? 
2)  will I receive a new one after the Finanzamt has received and processed the filled “Fragebogen zur steuerlichen Erfassung” form?
3)  shall I submit the form before I quit my current job? or can I do that any time after quitting my job?
4)  can I take up a freelancing opportunity before I have submitted the form to Finanzamt?

Tax number stays the same. It's dependent on the person, not the job.

And the rest of the questions are best posed to the Finanzamt directly.

But one should also be aware that there are also legal restrictions to freelancing. If one has a work permit it must specifically say that it is allowed. And one cannot freelance for a single employer, otherwise one is considered an employee. This keeps employers from illegally avoiding health care, social contributions and taxes that are involved with employing someone rather than contracting out.