as far as I've learned the avg is 7 months but depending on their mission it can be 9 months or even up to a year.
Until they go back home, obviously
As long as they stay babies is how long they stay babies.
a few of the sea animals cannot stay under water for a long time.
Marines are usually fighting in the sea, so if there were no marines, then there would be more attack's from other countries who came by using the sea.
4 Days
Yes you can
about 10 minutes
2 to 5 years
i think it depends on how long you stay in the sea.
Depends.
5 hours
Depending upon the species/type of the sea lion, sea lions babies usually stay with their mother for an average amout of 6-12 months.
the Marines call it boot camp. its 12 weeks long