A: You have to enable LEDs support in the kernel configuration. The config options you have to enable are: CONFIG_LEDS_CLASS, CONFIG_LEDS_TRIGGERS, CONFIG_MAC80211_LEDS.
A: You have to enable RF-kill support in the kernel configuration. The config options you have to enable are: CONFIG_RFKILL, CONFIG_RFKILL_INPUT, CONFIG_INPUT_POLLDEV.
A: If you have the b43/b43legacy driver built-in (not as a module), you must also enable all the LEDs/RF-kill options (see above) built-in (not as a module).
A: If your chipset is 802.11b-only or BCM4306 rev 2, you need to use b43legacy. All other devices, including BCM4306 rev 3, use b43.
You can also ignore this issue and simply compile both drivers, they will automatically detect which one you need by themselves and the appropriate one will be loaded.