I am still new to all philosophical l thinking so my answers will be simple compared to most here. To me, suffering is subjective. An animal half eaten by a lion has suffered, felt sorrow and pain but to us, it's a part of life and a necessity. Never thought of it this way but I guess nature will always have perpetual suffering for the unlucky so it's inevitable that some have to suffer in life for the greater good.

I don’t know, there must be a link between hormone and biological needs. Hunger is triggered by a hormone is it not? I don’t think it’s fair to dismiss it as an unintended side effect of hormones.

Reproducing is a biological need. The ways some will satisfy that need is immoral (talking about non consensual relations).