I think that the major point I remember reading (possibly from Elo's EAQ) was that it is kinda modular, with a common base (RedPower-Core). The major issue is that, if the bug turns out to be in that (if it's a major bug, it's a quite likely thing), then the module you have (world) wouldn't be correct anymore.
With respect to the alpha release thing, my standard response is "pipe down". Elo has decided that it will be released when it's ready, and that is her right as the creator and (I believe) sole developer of RedPower. The mod is, technically, her property, which she shares wil us out of the goodness of her heart, because of the donations, because the sky is blue, or some other reason known only to her. It is not required, and there is no right of access.
If you are genuinely curious as to the nature of the bugs, and the methods, I would direct you towards the redpower IRC channel, where questions will be asked and answers will be given, depending on the information available, and what she feels like saying.
The desire of server managers or players for aspects of any mod before it's released to the public is of little consequence. There is no contract, agreement, compulsion or duty requiring any mod author to release a scrap of code at all. Any sense of such is a flaw in understanding, and a holdover from the current entitlement culture (I'll hold my hand up to it myself, on occasion).
As to the curiosity aspect of everything, there's little more that I can say other than she is very secretive and private, which just makes people more curious. Doesn't get answers, just get's the desire for them. I admire the resolve, to tell the truth.
EDIT: Read it back, and it comes of as slightly angry/agressive. Wasn't my intention, I was just trying to restate the points made previously (people have short attention spans/memories, I know I do ... Oooh, kitty!).