No, they are adequate for many uses.
I use about 28-30 for that.
You can use drywall nails or drywall screws. I prefer the screws.
How big of a box? They are normally sold by weight.
You can use drywall nails (ridged) or drywall screws. I am not a drywaller, but have done lots of it and prefer the screws.
Commonly #6 gauge.
About 4 grams.
20
This is a joke right? Answer is - they're cheap!
Metal drywall screws are usually fit with a small plastic pre-grooved sheath which taps the screw into the drywall and wooden beam behind it. This results in a clean and secure penetration of the wood for each screw.
nothing
The most commonly used are #6.