See problems reported on http://mod-buildcraft.com/forums/index.php?topic=173.0

If you just save the source blocks and force a block update when it's placed in the world.
You probably want to update all fluids after the structure is finished to prevent random fluids everywhere.

Something along these lines, definitely.

Alternatively, used some code is the post processing phases to place flowing liquids exactly as expected.

Perfection is boring. I would prefer if there was still a few manual steps to finish up a new construction. Lighting a portal, placing down fluids, filling tanks, machines and other inventories with items.

That's not the intent of the blueprint system. However, the system is flexible enough, nothing prevents you from creating a blueprint that does requires these extra steps!

I don't really care that much, but don't forget that Minecraft is a game and that BuildCraft is an extension of that. It should not be strange that the player would actually need do something from time to time.

Anyway, I see the problem with blueprint sharing. Might be harder to use if it wasn't perfect.