I would run a test and see what other channels are being used around you first before setting channels. If you have congestion leaving the channel on auto might work best for you. The QoS setting shown just enables prioritization for voice and video traffic and is normally the default. Other than that I would leave the setting as shown.
Is this a single WIFI source or an AP that is part of a group. 100% transmit power isn't a good thing in many situations. For example, if you have the same SSID on 2.4 and 5Ghz, then you want the power on 2.4 lower then 5Ghz to help the clients pick 5Ghz over 2.4.
Also the transmit power of handheld devices is much lower than routers or APs. So a device may be able to receive a signal if you have the power at 100% but may not be able to transmit back.