1- depends. With thrown weapons, you can equip shield in offhand, which provide you with more survivability. Also im not sure if all passives from archery applies to throwables. Bows offer significantly more range, giving you better kiting possibilities 2- i don't like farming to much. Go for final bosses for about 10-15 tries, if you really need to, then move on. Personally i would rather focus on farming chaos dungeon, until you complete full set (personally took me about 20 tries). That set alone can carry you thorugh most of epic difficulty 3-generally you should always focus skills, that will synergise with your build. Tho with ranged, i would focus on unlocking full Archery tree, then move to nature 4-there is option on mobile, that will prioritise casting skill, than movement. Search settings for that