the 380 is a 9mm short
No.
No.
NO
My .32 cal. mold produces pure lead round ball that weigh about 47 grains or about .107 oz.
Let a gunsmith do it.
There are a lot of variables involved with the number of grains of powder in any given caliber round. Most importantly are the type of powder and the weight of the bullet. After that is the loader's preference as to the velocity of the round. For example, I load a 155 grain .40 caliber bullet using Ramshot Zip powder for a "light" velocity of about 1050 feet per second using 5.3 - 5.4 grains of powder.
The case of the 9x18 cartrdige is 1mm longer and the slug is slightly wider. In metric .380 ACP is 9x17.
15m
1972
50-400
It depends on what "best" means to you.