Not silly at all, and it's one of the great mysteries (and sources of grief) in the whole business.

Answers:

a. Yes.
b. Yes.
c. Yes.

Usually, (a) and (c) are the same, and (b) is increasingly contingent on (a.) In particular you will likely be charged more in fuel fines - total - by British Airways if they're ticketing and/or flying the first segment, as they will assess surcharges "downstream" on other carriers' flights.

AA is less prone to do so, although they will happily pass through fuel surcharges on BA-flown segments (with or without AA codeshare designations.) I don't know that the data base is broad enough to speak in general terms on tickets issued by other OW airlines. AA does proxy booking on JL and RJ - initiated RTWs, but the online tool is very buggy in these cases, so while it might seem like those tickets suffer less from fuel fines, actually consummating the sale online with these carriers is problematic.

As of now, nobody has cracked the code on how best (which also relates to where best) to avoid excessive fuel fines - a lot of it is trial and error using the (buggy) online booking tool. In addition, of course, the possible permutations of itineraries (with and without stopovers, open segments, etc.) is in the ?millions? so a comprehensive road map is probably out of the question.

Anecdotal experience with having the AA RTW desk issue tickets irrespective of the first carrier (i.e. as a work-around for the online tool) is mixed; I've had them quote me a higher total (related to more YQ) than the online tool on the same itinerary, also less. Quite frustrating, in fact.