The barrel doesn't move. The secret entrance is between the hay bales by the farm. Slide them left, then apart.
it is to the right of the castle, just keep going right.
you put it into the spaceship ontop of the mill
On the water wheel at the mill. (Far right side of the Mill area) You jump up to it
There is no well at the mill. There is, however, a rope, and a secret society member, and a hidden hovercraft.
You can get a bag of manure (but just one) at the farm near the Mill.
In the field between the castle and the mill. A farmer will give you a bag.
The mill is out of commission. The only way to get across the mud swamp is the hovercraft in the mill's attic.
The windmill is at the far right side of the island. There are three areas : the Village, the Castle, and the Mill.
Climb into the loft of the mill and hang on the short rope there.
The marsh is all the way on the right, go right from the Mill.
The saucer Excalibur is crashed in the mud swamp to the right of the Mill.
It is to the right, in the Mill area. The three areas left to right are the Village, the Castle, and the Mill.