1. There is an argument whether a non-kosher item that is mixed with kosher items of the same type renders the entire mixture non-kosher.
2. The Mishnah discusses how one may eat the meat of udders (and the surrounding area) of a kosher animal.
3. Milk remaining in udders is not the type of milk that can cause a person to transgress the Torah prohibition of milk and meat.
4. One must tear the heart of an animal or chicken open in order to drain the blood (if he wants to eventually eat it).
5. If something is prohibited by the Torah, a similar thing is permitted.
A BIT MORE
1. Rebbi Yehudah: A non-kosher item mixed with other kosher items of the exact same type makes them all non-kosher. Rabanan: The non-kosher item can possibly be nullified if there are many more kosher items, even of the same type (this is known as “Min b’Mino” – “a type mixed with the same type”).
2. One should tear the area that the milk is in and drain it.
3. There is an argument in the Gemara whether it is even forbidden according to Rabbinic law to eat/drink this milk together with the meat, as it is primarily considered a part of the animal since it was slaughtered with the milk inside of it (i.e. “fleishig milk”).
4. The Gemara in Kerisus (22a) explains that the Mishnah says that one does not transgress a prohibition because it is referring to a heart of a chicken which does not contain enough blood to be punished by Beis Din for eating its blood.
5. The Gemara gives many examples of this rule. For example, while blood is prohibited, it is permitted to eat liver (which naturally contains a lot of blood and tastes like it).