Thanks!
As for bats, the last-minute absence-of-decision is what makes them this way. I was thinking about removing damage from them instead though. So that they would fit in the role proposed by Blood's readme:
...They fly around, chirping and swooping down on the player, but rarely cause damage. However, bats have a tendency to swarm and distract the player while more dangerous enemies attack. Bats can also get in the crossfire between the player and an enemy. A misplaced shot with the Napalm Launcher at a nearby bat can cause an explosion in Caleb's face.Copied this
from BWiki, but I think I read something similar in readme back in the days.
The float/fly away forever is a bug, and it will be fixed.
The corpses floating is a weird bug that will be fixed too (but, strangely enough, I have tried to fix it many times before with zero success).
However, they have a silver lining that won't be away: if there's enough of them, you can climb on them to the heights by jumping repeatedly and letting them follow you from lower level. The most obvious example of this is on MAP09 (train station), right outside the train station. You can get Life Seed on the sloped roof earlier than when coming from inside. It also lets you fight through the station in different order!