I don't use DeVeDe so I can't help with settings.
I was asking about file format not the content of film.
If on the final DVD you have Audio_TS and Video_TS folder and a bunch of .ifo, .bup, .vob files in it, than DeVeDe has done his job.
At maximum bitrate/video quality (~9000 kbps) of DVD Video standard you can put just a little over 1 hour of movie on a DVD5. Average standard on a DVD5 is 120 min (~5000 kbps). The more you add in legth the bitrate/video quality will lower to fit on a DVD5.
You should stick to the standard (~120 min/DVD5) but if you are going to use a really low bitrate (~3-4 hours/DVD5) then you should consider making your video half D1 (352x576/480) it will look much better.