For the Microphone boost, I'd suggest trying it at the middle first (15dB), just in case 30dB causes it to pick up too much background noise.
For the second screen, remove the check for 'Listen to this device'. This option feeds the microphone directly to your speakers (like a karaoke machine), which is why you hear an echo with it enabled. This may be useful if you have someone else performing a speech and using headphones to monitor the recording.
The 'Playback through this device' can be left as is, it'll probably be greyed out anyway with the 'Listen to this device' unticked.
For the 'Advanced' screen, leave the default format as '2 channel, 16 bit, 44100 Hz'. If you set this higher, it could cause a problem with applications that can't handle the higher sample rate.