Marten - pressure ON and AROUND the wound, not a tourniquet above it.
OK, if the ID is correct, not poisonous. But bleeding, it's a predator, and you never know what carrion it might have been chowing down on. So seek medical attention as you would from a rat bite. Clean with soap and water beforehand if you can.
Snakes, in my limited experience, while genius-level compared to frogs (which are less intelligent than most kitchen appliances - in this universe, not the QC one), are not the brightest bulbs in the chandelier. They are, however, affectionate, and like wrapping themselves round any convenient warm object when it's cold. Arms are ideal. It helps them regulate their temperature. I'm told that having a carpet snake in the house is a good alternative to having a cat when it comes to keeping the place rodent-free.