For the updraft thing... the simplest solution would be that it affects lemmings in both directions, although that might be a little weird from a visual and realism perspective.
Personally, I'd say that if the lemming is inverted, the updraft either has no effect or increases the fall counter to splat distance (possibly accelerating them while they're inside the trigger region, although I'm not sure how badly this will affect Gliders). At the same time, if the updraft object itself is inverted, so it's effectively a downdraft, inverted lemmings are slowed while normal lemmings are accelerated. That's even more work though and it depends on if namida feels like any of this is worth implementing.
I'm no longer very involved in developing / maintaining NeoLemmix. My input these days is pretty much limited to funding the NeoLemmix website and giving input here and there; Nepster is now in charge of NeoLemmix for the most part.
