1> Google cayenne + Dr. Schulze + tinture and somewhere you'll find a recipe for making a tincture using hot habaneros and/or some other peppers.
2>Peppermint is not laxative. You should steep the Senna for a shorter time to avoid cramps.
3>Dunno what the actual effects the oregano tea has on the system functions and if will stimulate anything that will work at odds with the MC. The only tea mentioned by Mr Burroughs other than lax tea is mint.