Hi!
I don't know if you can do simulaneous wlan and BT RX - especially
since WLAN RX sometimes requires ACKs to be sent. :) But for
multicast, sure. You'd have to check the NIC schematic and antenna
switch programming to see if you can do simultaneous wlan RX (with no
TXing, eg RTS/CTS, ACK, etc) whilst also doing BT RX.
As for BT_ACTIVE -> powersave; I don't think you can get interrupts
based on that, but you can poll the gpio pin yourself and then tell
the driver to not transmit and/or enter sleep state. Entering sleep
state requires that you send some frame anyway to tell the AP you're
going to sleep.
-a