If you have a visa but no employer or work then what you have is an illegal visa. You will end up owing a lot of money to your visa provider with no recourse should he try to extort or blackmail you. And I'm not sure what you will face in terms of job prospects with an ag ec degree. You will probably get a very low-level job in an area not of your own expertise. Good advice - FIRST get a job, then come to Qatar. Your employer will provide a visa and everything else.
Mandi