iwpriv and signal strength

[David Goodenough]

I am sure that this first one was answered not long ago, but I have searched
both by reading the last 600 messages in the list and with google and I am
obviously not asking the right question as I can not find it:-

1) When in AP mode, how do I stop packets from one slave station being
rebroadcast to all the other slave stations?  Is it the iwpriv command
bridge_packets that I need to set to 0?

2) Is there anywhere a description of all the iwpriv commands?  I know I can
get a list of the supported ones for a card using iwpriv, 

3) Why is the signal strength shown in iwlist xxxx scan so different
from that shown by iwconfig when connected to another station.  I have
seen differences of up to 20dB.  Maybe I am misinterpretting the numbers.

I am using a 2.4.24 kernel, with the wireless-tools 27+27pre9 on debian
unstable.