If you're going into the Sound for sure you want a VHF. They now have models that have GPS built into them which is very useful. A cell phone can be used but if you have a problem, you have to call 911 and then they call the local CG for your sector. If a cell phone gets wet it won't work. If you don't get a gps unit for navigation, get charts of LI Sound, that is a must as well.
One other thing that can help a lot is a website maintained by the University of Conn. They have weather buoys that monitor weather in LI Sound and gives you real time local conditions.
http://www.mysound.uconn.edu/I always look at this (I am closest to the Western Sound station) to get an idea of the weather before heading out. Also on the VHF you have the weather constantly on channels 2&3.
You would be closest to the Eastern Sound Station. In that area are the Cross Sound Ferrys so that's something to be aware of .
Most people have a GPS hooked up to their VHF so the radio knows where you are and the newer radios have a panic function. You push a button and it sends a distress signal and your location. You need to register for a number that identifies you for this to work.
Lastly if you don't have towing insurance, I'd get it for sure, because a simple breakdown can cost a ton of money to get towed back to port. Its not expensive for what it is.
If I recall you have an H-180, right? If so I'd limit myself to days when its less than 15 mph winds for sure and less than 2' waves. Because while that does not sound like a lot, combined with other boat traffic and wakes it can be. Also, the first time out keep the bow cover on, make sure you have a good support underneath. Make sure your bilge pump works and it has an auto switch. If you only have one pump, you can do what I did, buy a 2000 GPH Rule pump, wire it up with large alligator clips and a hose. Just in case you took a lot of water over the bow, you would have an emergency pump you can put in the bilge and hook up to a battery that would pump it out much faster than the pumps these boats usually have (500 gph). You don't want salt water to reach the starter and pulleys. It will do a lot of damage.