My Thoughts:
1.) Yagami Light's major mistake that caused him to lead to failures is his countermeasure to his encounter with Raye Penber. The bus incident he prepared was proven unnecessary since Raye Penber no longer have suspicions on him due to his facade of a normal highschool student. Though I wouldn't know what the alternative future might be, he shouldn't have interfered with Raye Penber. It caused him to reveal his ability to control acts and death process of the target, and let them trace him easily by deduction. Until the end, the incident with Raye Penber was used against him.
2.) Kira's loss to Near, though it's due to the plot, does not necessarily mean that Near or/together with Mello beat him. Both parties have great ideas that could overwhelm each other, however, the difference is that Kira blindly orders his followers while Near fully controls his companions. If they were to hold a battle where they are in equal ground, who knows who'll win.
