For instance I want to know that as a foreigner, what opportunities I have to study in the USA as a doctor, which university I should choose, how can I finance myself, ect. Tryin just plain old google search only makes the problem bigger, either too much info, or not reliable enough, or a lot of missing info, a question like this would take ages to find out...so how would you do it? What is the fastest, most efficient way?

I find that forums that are relevant to your topic are typically the best way to get answers handed to you. Sometimes you have to wait a while for replies, and this assumes that you can even find an active forum dedicated to whatever you need to know about.

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Reddit is not bad if you can find the proper subreddit.

Quora.com is a question/answers site that seems to have good quality answers overall. Short of registering you can do site searches like:

site:quora.com some keyword