Han Xin was a great general but not a great leader. He was too arrogant but didn't take the opportunity to destroy Liu Bang when he had the opportunity.

Yes, he probably was. Both he and Xiang Yu were the two best warring generals of the time. I'm guessing he really looked up to Xiang Yu but when his talent wasn't recognised, it turned to hate.

I never really saw a good documentary on how Han Xin actually defeated Xiang Yu in the final epic battle. I mean detailed battle strategies and formations etc.

Although, after Xiang Yu was defeated, I think Han Xin would have known what would have happened but maybe he was too arrogant to take the necessary precautions.

Xiang Yu wanted a return to the orthodoxy, meaning various warlords ruling over the respective regions such as during the Zhou Dynasty. Liu Bang on the other hand, wanted to continue the system instituted by Qin Shih Huang Ti.

I think Liu Bang was the better choice rather than Xiang Yu. China would probably end up like Europe if he had won. Maybe not as fragmented, but probably split into 5 or more different nations.

I think most of those in rural areas had some rudimentary ability to defend themselves. After all, it's not like modern times. Imagine, if you're able to hunt and kill animals etc, you'd probably be quite hardy.