The delete click is the Delete button on your keyboard. The mpv file is the "video only" part of the stream/mpeg file(i.e. audio has been seperated, that file will be called mpa/mp2/some other audio format). So when you think about it, it should be smaller. As far as menu creation goes, it will serve you well to read the Help files in the program, they are excellent. To demonstrate to you how good they are "I have made 2 dvd's with 30 menus each and 15 home VHS clips, converted of course, 1 of them being a multi-VTS(PAL and NTSC on the same DVD). " All the help I needed was in the Help files. But YOU have to read them COMPLETELY not just the quick Tutorial In order to make anything approaching the look of a PROFFESIONAL DVD.
Also read the guide that Ikki mentioned. It helps only little.
Hope this helps.