For a snapshot of a clip in the bin, click on a clip. Then, in the preview window, right-click and Take Snapshot of Clip. For a snap of the sequence, click the timeline. Then, in the PV window, right-click and Take Snapshot of Sequence.
For the buzz, click the FX button on the audio track, then to green + sign at the top-left of the effects window. Play with the choices there, especially...high pass, low pass, equalization and noise removal.
You can also export the file to Wavepad, where there are extensive options. First, position the Videopad scrubber (red line) at the start of the audio clip.
Then right-click on the audio track and Edit With Wavepad. When satisfied with the result, close Wavepad and SAVE. The result should replace the audio track in Videopad. The file will also show up in your PC's MUSIC folder.