1.I would recommend you to visit Ukraine in summer. The weather in this season is very warm and you can visit many outdoors attractions.
2.In my opinion,Kiew-Pechersk Lavra and Urcin rocks are definitely worth seeing.What's more,if I were you.I would go to Independence Square.
3. I believe it is a great idea to travel to Kiew. Firstly,it's the capital of the country. Secondly,this city is very beautiful and interesting for tourists.