Ideal stats for a range tank are 99 range, 99 mage, 99 def, 99 hp, 75 attack, 75 strength and 98 combat if prayer/summoning are at 1. As far as quests, you will want to do Animal Magnetism, Lunar for veng, Forgiveness of a Chaos Dwarf for hand cannon, and dt would also be good to get once you have high mage. Use runescape.wikia.com for more details about quest requirements and everything else.