I think oro tried to kill naruto bcoz jiraiya told him dat Akatsuki were after him. Akatsuki were biggest threat to oro, so big dat during sasuke retrieval arc, oro said let konoha handle akatsuki. Maybe he was afraid of some of them, maybe he was afraid of pain, itachi and possible kakuzu, others were weak compared to oro...
Madara want Kyubi he wont kill naruto.
I also think sage mode defeats sharingan. Not actually defeats but make opponent able to counter Sharingan techs. But it can not be proven...