-process of working visa.

Get a Job, the company will give you a work visa.

-do i have to pass medical..???

Yes, everyone does.

-law of sponsorship (advantages and, mainly, disadvantages)...

Advantage: Free visa, Labour Law. Disadvantage: you are tied to that company.

-cost of living...???

Mainly European costs but lots of things come cheaper

-where should i loan an appartment (2000-2500QR)..???