A question about Zigbee Channel Scan?

Does this show only Zigbee channels (and not 2.4 WiFi)?

In terms of RSSI, is it true that the greater then negative value, the stronger the signal?
According to the wifi analyzer program that I have:
Good: -60 -> -40
Medium: -89 -> -60
Poor: -100 -> -89

No, your wifi analyzer table is correct; the more negative, the weaker the signal; but since the scan only measures RF energy in Zigbee channel bands, it can't distinguish signal from noise (or an overlapping wifi sginal )at the time of the detection.