#3
No snails in the bucket. Perhaps a couple of drowned garden slugs...
Size: about a centimeter, if I recall.
I really should have a tape measure handy when I take photographs...
#4
You do not need necessarily need a ruler to show size. Something of which we all know the approximate size will do. (For a landscape photo it is always useful to keep one person in the picture...)
My first guess for the larva is a species of the Muscidae but I will dig into some books and see what I come up with.