I fist got the Wi-Fi working directly connected to the plug and then plugged it in to the usb hub.
You might want to set that up again and do a scan with a direct connexion since
Quality=43/70 Signal level=-67 dBm
that is a very low signal level. Mine (a RTL8187B chipset Wifi dongle) gets this
Quality=70/70 Signal level=-6 dBm
and I only run the power at 20dBm (100mW). However, I have recently (yesterday) noticed that if I don't power the hub the signal gets weaker - particularly when used. I have a 4-port Belkin hub