Maloesie

To get to the cache you have to go back with the teleporters to the docks you got your boat from. Get another boat (there are 2 more you can take without trouble) and go through the rapids again. Somewhat before your at Harkin's Landing there is a piece of land. Go of board and search it. It has a couple of stone pylons on it. There the back wall will disappear and there is your cache! Good luck

I have the answer on question 4: you can keep the ceremonial items if you give them all to 1 partymember and let this member be killed by the friendly (if you have enough nature lore and before you attack him) worg (the wolf n the eastern parts of the testing area). After you let him be killed you exit the testing area and go to Shanker's tower and revive him. He then still has the ceremonial goodies. If you still have to go west of Shanker's tower, leave the items at the tower, otherwise you will loose them after all. You can take them to the rapids and beyond!!!