No, you cannot.
Yes. You can join the US military without being a citizen, so long as you've established permanent residence and have declared an intent to obtain citizenship.
As of 2011, gay people can freely join the US military and do not have to hide their orientation.
Yes
Height doesnt matter in the US
Sir Yes, Sir!!
Not in the US military, no.
Can't be done. While the US military does allow foreign nationals to enllist, it's done with the condition that they establish permanent residence with a declared intent to obtain citizenship.
U.S army
One can join the US military as young as seventeen (17) with parental consent
The Coast Guard is a branch of the US Military, so yes.
No - the minimum age to join any branch of the military is 17, and only with parental permission (signature on your entrance application). Those who are younger can of course join the various military schools and cadet programs around the country in preparation for later military careers.
In the Canadian Forces, yes. In the US Army, you need parental consent to join at 17, but you can't join at 16.