To loosen, have handle of spanner / allen key pointing to the rear of the bicycle and push down. Handy as sometimes I need to use my body weight
Personally speaking I don't tighten more than finger tight. I don't know what the required torque's supposed to be but my theory is that the pedals will, if anything, tighten
so I don't need to worry about them falling off.
My bold. As proven by brit_in_oz's mate's experience, your theory is incorrect. Here's how.... As noted, pedals are removed by unscrewing them "backwards" in relation to the bike (backpedal the crank for directional reference if you must; pedals are unscrewed the same way, either side). Now, turn the crank over forward, while holding the pedal to simulate it being held in position by your foot - by virtue of being stationary it rotates in the opposite direction
to the crank. So if a bearing was to bind, the pedal would unscrew from the crank, rather than tighten itself & tear the rider's foot off when it locked!