You cannot kick yourself. You cannot kick while in a pit or webs or the wilderness. Kicking while confused, stunned, or blind requires a Stat in Stat+40 check; Stat is Dexterity for blindness and Willpower for the others.
Kicking a door will succeed Strength + KickBonus times in Strength + 12 (112 if the door is secret). Successfully kicking doors will cause tension rooms to crumble, will always trigger traps, and trains Strength by +1. There is a 1 in 5 chance that 1d2 sticks will be created. Unsuccessfully kicking a door has a (14 - Strength) chance in 15 of training Strength by +1. If the door is trapped, you have a (Mana + 1) in 30 chance of NOT triggering it. If you avoid the trap, you will train Mana by +1. Failing to kick open an undiscovered secret door is treated as kicking an undiggable wall. If a secret door is kicked open and discovered at the same instant, it has a 10% chance of being trapped.
KickBonus is 0, +15 for Strong Legs, +Level*2 if Monk.
Level 13 and higher monks can kick down walls on a straight Strength in 100 roll. Non-monks kicking walls will take 1dN damage; N is one third of your Strength, or 2, whichever is higher. Add 2 to N if the wall is non-diggable.
Remains to be investigated.