Basement dilema !

Hi there,

I hope you guys are doing great. I had a few questions to ask about my in-progress basement that i needed some opinions upon;

1) my basement is 1500 sqft. I've built outer walls in rcc, then did zero size chips from outside and then had 2 coats of waterproofing chemical painted on the chips (using 'ultra chemicals' product). I also plan on using a plastic sheet on the outside before backfilling. Should i also do plaster from inside as well? Is there any water soaking chemical i should mix with the cement before doing the basement plaster from inside? Or there is no need of plaster from the inside?

2) is there a preferred soil that i should use for backfill or just any soil/sand is fine?

3) i have an option to keep the backyard (10 ft) open for the basement because of the natural level of plot (it's heighted from front access, and goes down as you go to the back of the plot). I plan on backfilling the backyard to give my ground floor the access to the 'sehan', and this way i wouldn't have to worry about rainwater as well. What do you recommend, should i keep the backyard open for basement access and air and ventilation etc, or should i go ahead and backfill it to enjoy my ground floor sehan for laundry? :)

Thank you for any advice you can give. Principally i think basements should be avoided as they're too much of a headache, but i wanted to set an example of probably the first non-seepage basement in islambaad (inshallah) :)