Sam, Loyal friend, bravest hobbit, or just scared

[MLD-Grounds-Keeper-Willie]

I get the impression that the success of Sam's part in the quest was due to a certain amount of blindness to the true dangers of the situation.

yep:

His naive quality at that point allowed him to miss the realization of what he was getting into.

but:

Being focussed on helping Frodo through everything confronting him would therefore take Sam's attention away from his own situation

I have to disagree with that. I think that when he was well into the journey, he was well aware of the danger he was in, but he didn't care as long as he was protecting Frodo. I think that he would give his life for Frodo even if he actually was aware of what he was giving up. He just would just want to do it for Frodo, and he would do anything for Frodo, that's how loyal he was. I do think he knew of the danger he was in.