In my opinion, although Donald Trump's area of concentration has not been foreign policy throughout his long and thus far extremely successful career, the man is brilliant. He will swiftly and effectively bring himself up to and even past speed on whatever he needs to know in order to deal with all foreign policy issues.
The United States is controlled by the country's funding source, not it's political leaders. The federal reserve bank is a private organization that effectively owns the entire US economy including the proceeds from every tax payer. Every policy and war is crafted and enforced towards the best interests of the owners of the nation, not the property of the nation.
Any leader worthy of the title of President realizes his or her weaknesses and finds (we hope) the best minds to advise them. I do not believe Trump has the foreign policy knowledge on par with someone such as Hilary Clinton but, again, he could have quite a Cabinet or inner circle to confer with. He has stated publicly that his intentions are to surround himself with brilliant experts should he win the White House.
I can understand why Vladimir Putin would like someone like Donald Trump. After all, Donald Trump says a lot of things that sound like things Putin might say. But in spite of all the tough talk, deep down there is no real policy with Trump and his arrogance can get the United States into a lot of trouble should Trump actually succeed in this election.