I'll try and answer your questions in order:
Look in the Hornady manual and you will find data and velocities for various Hornady bullets. The Speer Grand Slam in .375 also works well for deep penetration. There are also cast bullets for this caliber, although ported barrels may don't really mix well with cast bullets.
I have a Contender barrel in .375 that has been to Africa three times. It has accounted for zebra, blue wildebeest, eland, waterbuck, gemsbok, etc. These animals were taken with handloads using 270 and 300 grain Hornady bullets. The 220 Hornady FP is a very effective whitetail bullet and should do well on black bear. Others have taken everything from elephant on down with this caliber. It should suffice for your purposes.
I have not noted a change in the point of impact from switching barrels on my Contenders. In fact, many years ago I tested this by removing and replacing a barrel for each shot in a five shot group. I then shot another group without removing the barrel. I could not tell in difference in my .223 or .309JDJ barrels.
Hope this helps.