Regarding the talent vs hard work comparison, i think the author of the manga intended to subvert that. you'll see why later on in season four, but here, Oikawa was limited by the belief that no matter how hard he works, he'll always be surpassed. however, when he says "talent is something you make bloom, instinct is something you polish", he realizes that no, he isn't limited. and even though seijoh lost, he did a set up he never would've done in season 1 with the set outside of the court, and he finally realizes that he isn't actually limited by anything and he can do it.
Yes pro matches are like that. If you wanna see rallies like that watch Japan's womens team. Womens rallies typically last longer than mens but Japan's team is notorious for keeping the ball up. In the recent semi final match VS Brazil they were going crazy. Id so recommend watching (or even reacting 👀) to that match. I was LOSING IT.
