Thank you for sharing your thoughts on this !!H4: To visit your spouse you dont need H4. H4 is for people planning to become resident in US(that is, moving your home to US).
B: You should be getting B2.
H4 plan: Your plan wont work even if visa officer is not knowing your actual plan and stamped because you would get caught in your frequent travel in the first few trips itself. So you should plan based on that or you can take chances and stop commuting once you are giving warning. So choice is yours.
B/H visa: For now US is allowing only essential reasons. I dont think that if meeting family member is essential as Canada and US were not allowing meeting family members during the ban on non-essentials on both sides. So currently Canada lifted but not US hence ban will be applicable to you as far as i understand. It doesnt matter which visa you hold but essential reason is different thant what visa you hold.
Lets weigh in if other members are traveling currently to visit family members in US.
I know that family members are traveling on H4 visa to meet families but not sure if that is being used for frequent travel plans. Will see if anyone else has any thoughts to share on this. I am contacting my spouse's immigration lawyer as well. Lets see what they have to say about this.