Any circumcision is scary ass.
More Than You Could Possibly Want To Know Dep’t: I took the line connecting Crystal River and Daytona Beach to be the base of the “glans” of our wang, which means the Sunshine State is a micro-penis. 
IANAMohel
My city is often referred to as “Halfway up the [name of large river you’ll recognize]” although it is actually only about one quarter of the way up. It sits at one end of a bridge that is supposedly the longest in the world of its type. It’s also difficult to spell and pronounce.
Sounds like Memphis.
Yep. Geographically a small blue island surrounded by a huge red sea.
I live on the world’s most populated island completely surrounded by fresh water.
Yeah, I thought your description was a bit off, but there are still some things I do not know about the male anatomy.
If I’m correct, four sailors went overboard one day from a boat named after your two cities. A friend of mine was XO at the time.
Grand Island, NY?
Now do the neighborhood! I lived south of the make-believe factories, and close to the place named after a signer of the constitution.
I live on an island that’s in between Victoria Island and Ellesmere Island in size. The latitude is somewhere between Calgary and Edmonton. An insignificant port in the region leant its name to a much more famous city and party.
Quilmes?
Most populated island completely surrounded by fresh water is Montreal (Canada) - at the confluence of the St. Lawrence and Ottawa rivers. It’s in the “Hochelaga Archipelago”.
It’s a bit difficult to spot my country on this map:
Can’t tell if you reside nestled in the ass crack or deep in the bosom. How are you feeling today about your location?
My locale was once a stop on the Silk Road and where two rivers meet was docked the RE Lee.
I wanted to show the funny side of a bad description, but I like your ambivalent perspective too. 
I suspect this violates the 2-click rule.
Correct! 
The first two clues were easy but I had to google the third one.
I live on an island in a river. We have a mountain on the island.