Q 2: Is it permissible to
sell animals according to their weight?
Yes, it is permissible to sell animals according to their weight. In pursuant with Ijma` (consensus of scholars), it is also permissible to sell animals just by seeing them without having to weigh them. The food and inside-organs do not affect the permissibility of selling by weight, because they are part of a whole, so it is permissible to sell it by weight.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.