Won't lie. Losing Hemmer so soon was both shocking and a huge disappointment but it doesn't affect my respect for what the episode tried to do. I so wanted him to hang on for at least a few seasons before Scotty is assigned as Chief Engineer, but I guess if he had to go out in Season 1 this was as noble and fitting an end as any.
The Gorn must lose most or all of their tails by full maturity and become bipeds. And yeah, I side with the theory that their eyes become more compound as they reach adulthood.