Ahkittksc san,
こんにちは。
どういたしまして。You are welcome.
Regarding the first Japanese sentence,
忙しかった後で 再びここで勉強できたのは 楽しかった is better.
I know it’s direct translation and different from your original sentence however, that is natural.
Regarding the second sentence, yes that is perfect!
YobRivera san,
こんにちは。
Their sentences are good.
However, when you put に after 夏中, it sounds like your obligation or your plan.
I think that sentence indicates your feeling so I recommend you not put に.
One more thing is 氷入り is correct.
So the whole sentence is 夏中氷入り炭酸飲料を飲むのがさいこうです.
Yuki 由紀
Team JapanesePod101.com