Yes First part can be achieved .
For 5 Ghz use , “RTDEV_WPAPSK1”. Below configuration , I created .
For 2nd part ,In device UI also we support only 20Mhz and 20/40Mhz for 5Ghz , “RTDEV_HT_BW 0 is for 20 and 1 is for 20/40.”
SSID1=${SSID1=2.4G_Name}
WPAPSK1=${SSID_PASSWORD1=default}
RTDEV_SSID1=${5G_SSSID1=5G_Name}
RTDEV_WPAPSK1=${5G_SSID_PASSWORD1=default}