Ha Giang Loop in 4 Days by Bus

Hello, I’m planning a trip to Vietnam with my partner, and we’re considering Ha Giang in October-November for 4 days on-site to do the loop by bus, since we’re not old enough to ride motorbikes. I see there are sleeper buses—how does that work for sleeping at night, meals, etc.? And what are the rates per person for these 4 days and nights? Then there’s Sapa—what’s the most practical way to travel between the two, or should we return to Hanoi? I’d love recommendations for simple but decent hotels and any other tips you have. Thanks so much! !