If you're seeing more incoming searches in your monitor than you did before, that probably means that you're just sharing more files now, so more searches make it through to you. That said, seeing the screen fill up with searches within 30 seconds is a really moderate number of searches to see, and that should take up very little bandwidth.

On the connection settings, I'll have to ask Chris if he did this intentionally -- it might be a bug, or it might be there to more actively limit the number of connections that leaves can have.

On the "bars" I'm really not sure what you mean. Menu bars? Tool bars? Scroll bars??

Back on the bandwidth topic, there's no reason that 2.4.1 would take up more bandwidth than previous versions, as this code has not been modified. I strongly suspect that you're simply sharing more files now. Is this not the case?