I got a logical explanation for some of your complaints ...
1.you know how sometimes death is quicker and easier then going through torture and living through/with pain ? well going to the phantom zone woulda been worse then dying.
3. jonathan kent believed that there will come a time in the future where clark will be vital and save even the whole world.... but if he exploited himself at a young age something could happen to him that could ruin that possibility of clark being a savior.
4. think of it like this.... you father repeatedly tells you not to smoke, but you smoke all the time when your father is not around.... and you have a discussion with each other with your father talking in such a way that if he finds out that you smoke again that he may/will never forgive you...then you find out your father is about to die.....are you going to smoke infront of him ?
5.their systems needed time to adapt to earth
6.personally i don't think he fought that easily.... plus with superpowers like that... it's not like you have to know ju jitsu
9.i think that zod's adaptation yo earth was still in the process and had not fully developed... clark has been on earth for years and matured on earth... therefore zod was weaker.