A Bug and a Bum

I was walking into a park on Monday where I like to sit and read, and I witnessed a few interesting occurrences. This park, located near city hall, feels at least slightly secluded from the city thanks to a nice cover of trees.

First, when I walked in I heard this very loud sound that was like a 'WEEEE WEEEE WEEEE WAAAAAAAAA' with the 'WAAAAAAA' decreasing in frequency. It took me a few seconds to realize that these were bugs making this sound. I looked around for bugs, well, mostly listened around, and spotted one on a light post. I watched it as it made this 'weeeee' noise, incredibly loud, then flew away.

The bugs look to be about 1.5 to 2" long. I did manage to snap a few pictures:

Does anyone know what these creatures are? They just make this incredibly loud sound that I can sometimes hear in the morning outside my window.

I should mention, I also caught another interesting sight. I found a man passed out on a park bench with a giant bottle of soju next to him. It was noon, mind you. Actually, this isn't completely uncommon.