Would these boots work in Boston in fall, winter or spring (or any combo thereof?)?

Those boots are meant mainly for winter. You can probably wear them in early spring when it's just starting to warm up and for late fall when it starts to cool down. It's probably too warm for summer, and I think you would look kind of out of place with furry boots in the summer. Boston can get quite cold in the winter, so those boots should keep your feet warm. Spring doesn't really warm up until late March or early April. Fall starts to get really cold around Thanksgiving.

If its cold they will be great but if its slushy out it might be a problem if you step in a deep puddle

If it isn't slushy or snowy in March, I'd probably leave them at home..