Any standard DVD must be MPEG-2, no variant.
The settings in the project depend on the main source material you use. What, how, why they are, comes only to 1 point: they (are correctly interpretered on the time line and) relax CPU’s muscle, e.g. you have ntsc hdv material but your project is set to pal hdv then the cpu suffers decoding/transcoding all the time and you yourself work also very heavy.
For which field first etc., there’s no relationship between source and your end product. That’s why it calls RENDER AS…
The issues about flickering and so on are big themes that not only amateurs but experters always confrnt. We should learn more, then could solve some of them.