Actually, the mean admin mod supports the very feature you are asking for. There is a check at the start of each round to see if any humans have joined or left and adds/removes bots accordingly.

As for the bots themselves:
A$$A$$IN - I think it's called a WIP for a reason. Stefan hasn't implemented all of the CS/bot features yet. He pretty much re-coded everything from scratch (didn't use RealBot AI code). The coding aspect you were suggesting doesn't sound to easy to code, and would probably use up more power since the bot would always have to be checking if it's stuck.

Also, if you read the progress thread you'd see that the CT standing on top of the bombs has been fixed for next release. As for the bots shooting before they see you: my guess is it's the early 'hearing' code; the bots auto-aim you through the walls until they can shoot through an obstacle to hit you for now until Stefan properly codes them hearing you walking or attacking.