is eating my twins placenta wrong?

Not in the moral sense, but it may be unwise.

One function of the placenta is to absorb any persistent harmful substances, such as lead and mercury, to protect the foetus. It would not be a good idea to eat a placenta containing those.

There are a lot of companies promoting placenta pills with claims that the can cure all types of maternal maladies However, the business is unregulated and the claims unstudied. I found one woman online who regretted taking the pills because they seriously messed up her physical and emotional condition. Others claim to have benefitted from them. So, in the end, it is up to you, but be aware that the industry is unregulated and the added ingredients in the pills may affect people differently.

Yes

Yes. It has no health benefits or anything. You're not an animal.