Working visa without a job offer

Hello,

I've read that several nationals (I'm Israeli) can get a residence permit (and therefore - a working visa) in Germany while applying from within the country, due to an agreement that Germany has with several countries.

Could somebody from the "privilege countries" list tell from first hand how the process is done?

Do I just have to have a renting contract (no matter in which city, right?), a health insurance, a German bank account with sufficient funds, an appointment with the immigration office - and I get a residence permit + a work permit? No job offer is needed, correct?
How much time does it usually take, from the appointment scheduling to their "verdict"? And how many times do I have to visit the immigration office for this matter?

Thank you