This reminded me of a fantastic and short Ted Talk about followers: http://www.ted.com/talks/derek_sivers_how_to_start_a_movement?language=en#t-1426

This resonated with me. I'm not prone to be the head of leadership, or to be a "hero". I do like being an early follower, however. Someone who can lend strength and support to a cause I see as worthwhile. In the parlance of the Ted Talk, I like to look for lone nuts to turn into leaders by following them. In this way, I like to think of myself as leaning into the role of selection as a follower (such as a Samwise), playing off of variation (all the lone nuts out there), and allowing for favorable evolution (of whatever).

Canon!ArthurWeasley isn't very knowledgeable, but he at least had an interesting in electrical power, heavy-than-air non-magical flight, and chemical fueled engines. I think we can expect him to be of similar intelligence or smarter in MoR.

I don't think so, per chapter 61:

Madam Bones's voice continued. "We brought in Arthur Weasley from Misuse of Muggle Artifacts - he knows more about Muggle artifacts than any wizard alive - and gave him the descriptions from the Aurors on the scene, and he cracked it. It was a Muggle artifact called a rocker, and they call it that because you'd have to be off your rocker to ride one. Just six years ago one of their rockers blew up, killed hundreds of Muggles in a flash and almost set fire to the Moon. Weasley says that rockers use a special kind of science called opposite reaction, so the plan is to develop a jinx which will prevent that science from working around Azkaban."

...

"Severus?" the old wizard said. "What was it actually?"

"A rocket," said the half-blood Potions Master, who had grown up in the Muggle town of Spinner's End. "One of the most impressive Muggle technologies."

It seems pretty clear from chapter 61 that MOR!ArthurWeasley knows precious little about the muggle world.

I agree that it would be a useful exercise, but given constraints of time as well as opportunity cost, Harry may simply be prioritizing other pursuits.

More likely still is that people really don't think on the matter much and so don't have well formed or necessarily consistent views of souls.

The reference in the text doesn't state anything more than that it was a snake, not that it was a Blue Krait. We don't even get to see Harry's reaction, be it familiarity or perceiving it as novel.

The snake is described as "gleaming soft white" and "silver", which fits with the description of a patronus. And as it doesn't match the description of Quirrelmort's animagus snake "bright green and intricately banded in white and blue", it is clearly not Quirrelmort's animagus form.

While I assign a much higher probability that we just saw Drako's patronus, we can't rule out the possibility that it was someone else's patronus, including Quirrelmort, even though I see those odds as being exceptionally low.

I strongly agree, but I'm still left wondering how to interpret the rest of the prophesy:

And the Dark Lord shall mark him as his equal. But he shall have power the Dark Lord knows not... and either must destroy all but a remnant of the other, for those two different spirits cannot exist in the same world.

Edit: The prophesy still seems to be a good fit for Quirrelmort for this second half, but Death for the first half. I'm left wondering if there is some important relationship between Death and Quirrelmort that may resolve this.

We know that Quirrelmort is afraid of death (as is Harry's dark side), and that Harry is entirely sympathetic to that view. Voldemort/Riddle/Monroe seem to have an aging effect on Quirrel's body. Could it be that Voldemort/Riddle/Monroe have engaged in some sort of arrangement with Death to secure their own immortality? This would make the Quirrelmort character both ally and enemy of Death, and complicate the interpretation of the prophesy as well as Harry's course of action.

We already know that Draco's patronus is a snake, and it is reasonable to assume that Quirrelmort's patronus would be a snake as well (given that he's a snake animagus).

Perhaps, but the forest offers better isolation if he's more concerned about being disrupted from his thoughts.

I'm repeatedly seeing 'Monroe' spelled as 'Munroe'. Is this due to a disagreement about how the name should be spelled, a common spelling error that has perpetuated in these forums, or is it a shorthand reference to some prior discussions or concepts which I'm thus missing in my reading on these discussions?

Or rather, he simply want to know what Harry knows so he can produce an even better model of Harry and improve his influence over him.