It depends on which model. Not all handguns are the same in the way they operate.
380 auto. Many good brands of ammo out there.
Many makers offer firearms that shoot the 380 ACP.
Try want ads, gun shows, gun shops.
gun shows, gun shops, want ads
Russian made
30-400 USD or so
2mm in case length.
100-1000 depending on exactly what you want/have.
You don't define what "better" means to you. Price? Size?
Near the firing pin
$75-$125, depending on model and condition.
Best left to a gunsmith