New England states (with the exception of maybe northern Maine) have effectively no social conservatives other than some fringe people. This means all social issues are settled. No reasonable middle of the road voter there thinks a fetus is a human, that religion should be a big part of politics, or that there shouldn't be gun control.
Therefore there is clarity on what the issues are. So for local issues the GOP candidates tend to only distinguish themselves on taxes and fiscal policies and don't need to run to the right during primaries. California and New York are larger and more diverse states that do have pockets of social conservatism and therefore GOP statewide candidates tend to run to the right to win. This is the same issue in Virginia where GOP candidates need to say stupid **** in primaries (or conventions) to appeal THG-level religious people then become totally out of touch for the general electorate and lose.
1. Why do you feel the need to single-out THG when this has nothing to do with him. There's also a ton of anti-gun control liberals across New England, especially in the rural areas, although you're right about most of the region not being socially conservative. It's still "country" in a lot of ways though in the rural areas. For example, it's not that unusual to see pickup trucks in Bernie bumper stickers for example.
2. There's pockets of social conservative predominately Catholic-working class areas on The South Shore especially in Bristol county, but it's not as frequent as in other areas of the country like The Midwest/South.