MCH, you make some good points.
🙂 If you haven't guessed it yet, I actually just realized I like doing all that theorizing, not totally sure why though
The 29 number (ShameFame, this answers your question) was given by chagramama as the number Dr. Rawls said was on the first WL, and the same source said at least the Thursday, March 4th emails were in the first tier. We're kind of assuming the 3/5 emails are also in it.
All my theory counts on those assumptions being correct, and I'll say I'd expect my theory to be flawed sooner than what I just mentioned above.
Good questions (and someone else with more insight can help me out):
(1) I'm not sure if we know, but I would bet they replace an IS applicant with and IS applicant - not ranking their WL gives them the power to control the exact makeup of their class, and I bet they want to keep the 25/75 ratio.
(2) I don't think we know about this one and I'm not sure what to think. I would say they at least try to replace applicants with another who has similar interests/background etc. If they can ultimately get sex/race demographics the way they want, it's a plus. But I definitely could be wrong.
(3) Yeah, there will be less movement b/c of the backfilling, but some more b/c of OOSers. It'll probably ultimately be less, but who knows by how much . . . Does anyone know if Tucson backfills?
(4) Hey, that's a good point!

Haha, I think you're right on that one (110 invitations + 125 WLers + any Tucson backfills? = at least 235 of 550). Do we know how many people Phoenix interviewed? If there were 2 'tiers' of 29 each, it'd make a total of 48 invitations + 60 WLers + # of backfilled spots = around half of those they interviewed; though they could interview many more, but their small class size only accommodates that much. Anyone know how many they interview?