The only way to know is to experiment with as many different loads as you can find.
no
You will have to call Browning to find out.
Depends on what the barrel is choked.
You must contact Browning for the answer so you don't void your warranty
Depends on the ammunition. Rifled 12 gauge slugs are accurate to about 150 yards
Yes
Shooting rifled slugs is the ONLY way to shoot thru a smoothbore for deer. If you shoot sabot slugs thru a smoothbore, it will not spin and therefore not be accurate. For accuracy, the slug must spin out of the barrel. Either shoot a rifled slug thru a smooth barrel, or shoot a saboted slug thru a rifled barrel.
What it is chambered for. Shoot as many different loads and pattern.
no slugs should on be shot thru a improved cylinder shotgun. if you shoot thru any other choke it can cause the barrel to split
A rifled cannon can shoot approximatly 500 yards. The rifled cannon is a great weapon. I advise you to use it(if you have one) in a space between 600 and 700 yards.
Only if it is chambered for them. Have it examined by a good gunsmith
Lacking a slug barrel, improved cylinder works best for slugs.