Fresh Fish - welcome back to Boston & welcome to S-B ...
There is a list of Mass herring runs here:
http://striped-bass.com/regulation/massherring.shtml from last year. I have not found any changes officially although I know there is some.
Couldn't tell you about best ways to keep them long term because I only fish them live. Otherwise I'm using eels or plugs or another live bait.
Squid - personally know of nothing in the Boston area. Everything I know is in Rhody or out at the Islands (I'm not allowed to reveal much due to penalty of death
)...
Again, welcome aboard...