Need help with a few hard parts in this context - MC is talking with a male classmate, about the final test exam and the summer vacation

Question

Context: MC is talking with his friend about the final test before the summer vacation start. His friend is confident that he will pass the exam (with an acceptable grade, enough to pass the red mark :D) and be able to enjoy this summer vacation, since last year he failed and had to participate in the summer supplementary class.

There are a few parts which I don't understand much, so much thanks if anyone can explain their correct meaning to me.

More context below:

大和 (MC's Friend)「はぁ～、今年の夏休みこそは可愛い彼女をゲットして、ウハウハな人生を送りたいもんだな」

MC 「ウハウハねぇ」(my guess: "You want a rich (?) life huh?")

世の中、うまく出来てるというか、何というか、そういうこと言ってる奴に限ってできないんだよな。 (my guess: "In this world/society, I'm sure the people who say things like, how should I put this... "I can do this easy", normally will fail." ??)

そんなことを考える俺をよそに、大和は一人ニヤニヤとして涎を垂らしていた。

Answer 1

うはうは means lucky/happy, typically associated with making a lot of money as seen in examples in the linked entry.

In the sentences of the questions, it describes 'having a girl friend'. So the first part means something like

• Ah, this summer I'm gonna get a pretty girl friend and have a gorgeous life!
• 'gorgeous', huh?

As for the second phrase, そういうこと refers to 大和's phrase, so そういうこと言ってる奴に限ってできないんだよな means guy who say things like these are exactly those who won't have girlfriends. できる here means 彼女ができる = have a girlfriend.

世の中、うまく出来てるというか、何というか means literally This world is well made, or what to say.... It expresses the speaker's feeling ironical about the reality (those who are very willing to have girlfriends won't have them). 世の中 can also be understood as a part of the main structure as you did.