60" to 72" should be fine. I bought a 72" for my B3030. I wish i had bought a 84". You want it wide enough so when you angle your blade your tire tracks are covered.
A 4ft or 5ft would be what you need. As far a the HST it will do fine in low range. You might want to put some weight on the blade itself it might work better.
*Even the little BX1500s are.
That said I'm sure a B2410 is.
I'd be using a B2410 today If i had not discovered the BX23 before i finalized the deal on the B2410.