A great opportunity

It's been (we don't use the verb 'to have' when talking about time, only 'to be') a few years since I started to dream about graduating in the US. It would be an amazing opportunity to learn about new cultures, new thoughts and new contents of the college course itself.  (The last bit 'news thoughts....' makes sense but it sounds a little odd. I would say: ...about new cultures and ideas.)
Recently, I've received an e-mail about the Yale Global Scholars program, which offers a fortnight summer course at Yale on classes about politics, law and economics. As I am interested in politics and societies, I think it would be an amazing life experience.

(to suppose means that you agree but don't necessarily like.  Also, 'life' in this context is an adjective therefore it needs to be in front of 'experience')
Since I have to pay some expenses to apply for the program, I've looked for some financial aid, and, maybe, I've just found a backing. I am working really hard to get this opportunity. Let us wait for some news.'

('taxes' are a some of money that you pay to the government, and only to the government. 'expenses' works better here, but this word is quite formal. 'to do great effort' is not a verd in English, we would say, 'to try/work hard' - 'really' is added to emphasise. Also, 'surely' is a word used in cases like: Mike eats 10 cakes a day. Other person: But surely he must be really fat then if he does!  -- It is a hard word to explain how to use but the context which you used it in didn't work.)