On the matter of Red Cloak's Strength, we don't really know it.

8 is the assumed amount on the forums because his strength score is never really called into question, since as has been noted he is a caster specced Cleric. There are two problems with this:

1. Goblins are also inexplicably Medium Sized in the oots world, throwing at least some doubt on their usual racial modifiers.

2. Attribute Outliers are known to exist, take Roy for example: he is described numerous times as having above average scores in basically every area, even the mental stats which as a fighter aren't very useful for him.

Given those two points (more the second since the first is completely unverifiable) its possible that Redcloak actually has a very above average strength...but so prefers channeling the divine powers of his god and artifact that he has no desire or even need to put that high strength to use. If we take that into account, Redclaoks natural strength could be as high as 16 (18 roll with -2 race), and Bull's Strength (prepared for the Heist) would take that to 20.

With a 20 Strength he could lift off ground 800 pounds, and that would much more nicely explain the scene.