Autodisconnect should have its own menu entry under Settings in the area: Connectivity. If you don't have that, you don't have Autodisconnect installed.

Bleeding-edge drivers are by lxp, they have to be downloaded separately, if you do not know what it is you do not have it installed.

If you do have WLAN Transmission power set at 100mW, what about Power saving? have you set it to Off?

When you say you can't surf 5 minutes, you're not being clear. Is it the first 5 minutes upon being connected to your WLAN? or is it 5 minutes and your device is disconnected from WiFi?