1. BK Avatar is bugged when some Monster get poisoned i think. Some weird bug which i hopefully can fix for the next version. Have it on my list for long.
2. To get into the temple, use the fountain in act 5 (big clear area next to town). So you can take nihla wp. I wont change anything there, because running to nihlathak takes 1-2min maximum, even without maphack.
The guy in sewers 2 just got the key as extra drop. Beside of this he is the only mob which can drop mythical ore, which is required to craft a pretty nice weapon. Don't go to him for farming keys.
3. The charm system is one of the oldest thing in ROS which will stay. Also the dolls will stay, its not hard to get into the desert (maybe 30min) and u got a plenty nice amounnt of skills/stats for that upgrade.
4. As often said: USE THE DATABASE!!!
http://ros.freiik.de/itemdb/cube/Look for shadowsplinter jewels, first upgrade can be rerolled as often as u want. In the end u can get, wit some luck, a 50%ed, ll, @ jewel, which should be the best in the end for barb.
Also in uber can drop unique jewels which give indestruct + stats, some are useful too. Or may search for unique jewels which give +splintershot/+throw mastery to boost dmg.
In the end, you may post your barb gear/skillpoints and i can help you. My last barb had like 50-60k damage and ~6.5k life. Pretty sure u missing something.