Just wanting to pick one part and take a shot? That's cool dude, not everyone has what it takes to make a complete response.
And let's thing about this.
Can Marines do the Coast Guard's job?
No.
Can the Coast Guard do the job of the Marines?
No.
There is some cross over, but that isn't the point. Sure sure, the Coast Guard does a lot to keep the country safe, but they do NOT do more than the Corps does for the country.
When I say (to a normal person) major branches of the military, they will tell me 'Army, Navy, Air Force, Marines". Coast Guard is considered military by very few people, and I don't even know if it is officially except in time of war.
Which part of this post are you going to nitpick?