There really isn't a guide to this game, most of it is either self explanatory or is already described in game. To answer you questions, power stones are found in the dark dungeon by defeating the end boss. Transferring upgrades is done through your inventory menus and costs 70 souls each time. You simply select the item with the upgrades you want to transfer, select transfer upgrade, and then select the item you want to transfer the upgrade to. Note that ALl of the upgrades will be transferred. Good luck.