05-09 legacys are great cars.
They range from 9-18k+ depending on year and mileage
I'd look for a manual transmission if you plan on modding it and to me, they are better in the snow as you are in control
Snow tires along with it and you'll be fine in the winter
Insurance is going to vary on the persons history and record but its a family sedan, so it'll be cheaper than a 2dr sports car i would think
Spec b is just a 6spd transmission really. A few other things "better" but it''s just really a 6spd vs the 5spd in the gt