Spacing some stones would keep your wonderful neighbors from turfing your lawn and then you could grow some nice groundcover too. Depending on how high you want the stuff to grow, there is so many ground covers you can choose from. Vinca is nice, you can get a few colors to choose from. The deer/rabbits/mice/moles/voles etc don't eat it. Not sure how good it is for erosion control. You could also try bundle flower (desmanthus illinoensis), it's a perennial, for erosion control, and it's got decorative seed pods and is native to the US. It's hardy to -20, so since you are in Ma, not sure if that will survive or not, unless you use mulch. I got some to try where we have erosion problems, you can purchase it at horizonherbs.com, they got some interesting seeds and plants, and they have great customer service. You can also plant crownvetch, but it can be invasive and I personally don't like it. There are also shrubs that can help control erosion like candleberry.

We're new here too - but here goes: Your home is nice, and it's symmetrical (windows & then door is centered). You could create an additional path straight down to the street (more symmetry, if you like it), and maybe small decorative fenceposts or other structure down at the street to make a strong statement and delineate the property. It might give the 'parkers' pause if they think they're blocking your walkway? I like the idea of large stones and vinca or juniper along the street too to make a strong edge. Good luck!