If you mean as an example .270 Win, the Win stands for Winchester as they were the originator of the cartridge.
.243 THOUSANDTHS OF AN INCH DIAMETER BULLET. WIN SIMPLY IS SHORT FOR WINCHESTER, THE ORIGINATOR OF THIS CALIBER. THAT DOES NOT MEAN ONLY WINCHESTER MAKES GUNS IN THIS CALIBER. MANY GUN MAKERS CHAMBER THIS ROUND. IT IS A GOOD DEER, VARMINT, COYOTE ROUND.
Caliber is .243, buy ammo in .243.
Which caliber?
yes
It depends on what you mean by measure, but if you mean in regard to the "50 caliber" part, caliber is the diameter of the piece of lead.
Best left to a gunsmith
30 caliber with 30 grains of powder
What caliber is it... 30-30 WIN, 32 WIN SPL, or 25-35 WIN?
9mm IS the caliber. If you mean what is it equivalent to, it is approximately the same as a .38.
The 08 is referencing the parent case, the .308, necked down to accept at .284 diameter bullet versus the .308 caliber. Other variations of the .308 case: .243 Win, .260 win
Not very popular
100-1000 and up depending on specifics