Of the branches of the military in the US, I know someone from every branch except the Coast Guard.
Really? I have always wanted to know more about the coast guard and military in general as I have no experience with either
The Coast Guard is a life saving unit and wasn't actually considered a branch until 1915.
What are the requirements to join or be accepted into the coast guard?
I'm not sure, but would think similar to other branches: part of signing up for draft, then sign up and pass physical.
Does the coast guard help with border control?
I know for sure the coast guard is also a border guard in Germany and the Ukraine.  I THINK it also does in the US.