Shouldn't the test be about alignment, rather than the exact size? I that case the power-of-two stuff shouldn't matter either, as long as it's properly aligned. I do have an initial patch for native NPOT support, but it will (of course) only work on cards that support the relevant extension.
In theory yes, but there are games which depend on the exact pitch :-( (Warhammer 40k is one of them I think. This is what the registry key is there for)
I think we should switch to NP2 repacking by default(and fix it if it is broken), with that we can offer the correct pitch without the NPOT extension too.
Just as a sidenode, ddraw seems to work different. I suspect it has 64 bit alignment and a special case for 1x1 surfaces, I need to track that down too.