I think you need to read those verses where in the Quran it says "Obey God, obey the messenger" in context. My thoughts are that those words directly address the believers at that time. The prophet could only judge by the laws revealed in the Quran. The prophet could not come up with his own laws or prohibitions.
The reason why the vast majority of Sunnis and Shias find it hard to question the hadiths is because that's how they've been brought up since they were a child. The fear has been instilled in them and very rarely they will read and understand the Quran and question it's contents or what their community practices. If you read the Quran then you'll find God does not want you to blindly follow his words otherwise you'd be like the idol worshippers in the past.
There is no scholar who has any other source of divine revelation except for the Quran, Gospel and books from the Old Testament. Other sources can be used, such as hadiths, historical documents, jewish books, etc to explain verses in the divine revelations however when they are then the scholar should cite them when explaining them. It should not be a mystery as to why a certain scholar believes in such and such thing. I think far too many people are scared of actually reading up on the revelations and other sources. It's not difficult and it's actually very intriguing.
I believe God will guide you and explain his revelations. There's no need to be afraid of reading and wanting to understand Gods words without the help of a scholar.