Greetings and welcome to the CG family. The Key Largo is a 110' Island class patrol boat. She conducts a number of missions, including maritime law enforcement, search and rescue (SAR), and fisheries enforcement, due to the fact her homeport, Gloucester, MA, is major fishing hub. Your son will be what's known as a non-rate, meaning he isn't a rated petty officer yet, since he hasn't been to his A School (specialty training) yet. Non rates do a lot of grunt work aboard ship, but the other thing they need to do is get their basic qualifications out of the way so they are a functioning member of the crew. Aboard ship, this might mean getting lookout qualified, boarding team member qualified ( to be able to do law enforcement boardings),among other things. Being a non rate sucks, but everyone has had to deal with it. He needs to look at this as an opportunity to show the crew what he, as the new guy, is made of. Is he the kind of guy that will whine about having to do the grunt work ( that attitude will not get him far), or is he willing to take on the crappy assignments with a smile and a positive attitude and get it done?
He will typically live on board until he has all of his qualifications signed off. If there is Government/Government leased housing in the area, then he will be able to move there. If not, he will live on the economy, basically he'll have to find an apartment. The CG provides a tax free Basic Allowance for Housing (BAH). This is based on paygrade, zip code, and whether or not he has dependents. BAH for Gloucester for an E-2 without dependents is $1755.00/month.
Your son will be assigned a sponsor who will help him get settled in, learn the area, etc. He'll typically know who this person is prior to leaving boot camp.
Again, welcome to the CG family!