Q. 2) See question 3406 above. Do other body parts as internal organs? Appendix, Eyes,  Kidneys, do they have to be buried? If yes where and how?
A. Poskim disagree if there is a mitzva of burial on every part of the body even before the death of the individual. Mishne Lemelech (end of H. Avel) and others maintain that there is no burial obligation, to anything less than the head and majority of the body. (Based on the Yerushalmi Nazir 7: 1 and Semachos 4: 8).
Tosafos Yom Tov (Shabbos end of p. 10) opine that even a ‘Kezais’ (or olive volume) of a cadaver, should be buried by itself. Gesher Hachaim (ch. 16) is of the opinion that all agree that when possible these parts should be buried with the main body.
Noda Beyehuda (1: Y.D. 90) regarding the burial of a fetus argues that the liability of burial of body parts is to avoid incurring in the prohibition of benefiting from the death. While Gesher Hachaim (ibid) indicates that it is mainly to avoid the prohibition of Cohanim to come in contact or close to parts o a cadaver.
Chassam Soffer (336) adds that it is due to the inherent holiness of the body of a person, which is similar to a Sefer Torah.
However, Shevus Yaakov (2: 101), Maharil Diskin, Tsitz Eliezer (10: 25) are of the opinion that even if there is no obligation, the minhag is to bury them. And on the onset and when possible all the body parts should be buried together.
Horav Shlomo Miller’s Shlit’a opinion is that the burial obligation applies mainly to body members that have bones in them.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a