I know to move the slider under compression to 100%.
I am sorry, but I have to ask: how do you "know" that? I "know" to always leave it alone. Quite a few users put it up to 100% but I always leave it at its default of around 70%. It is not actually an indicator of quality per se. It is an indicator of the quality you might be able to achieve and the time it might take to achieve it. The default is supposed to represent a reasonable time to to achieve good quality. Raising it will significantly incease the time factor, but the increase in quality achieved in that time is relatively small, if detectable at all. Personally, I have never been able to see any significant difference -- and believe me, I am a Virgo perfectionist!! Others swear by it.
What I *do* know is that people who slide it up to 100% but don't have particularly powerful computers often find that their project starts stuttering or comes to a complete halt... We usually recommend in such cases that they reduce that compression slider significantly -- down to 90% or less.
As for the rest of your post, like mitchell65 I have some difficulty in following exactly what you are after when your provide no information about what you are inserting or what editing you have done or even what you are trying to produce. I am also assuming that you are talking about the burning module... But looking at some of them:
The 'Do not convert compliant mpeg files' is important if you have inserted DVD-compliant mpeg files into the burning module. If ticked, the files are not then re-rendered as part of the burning process. Nor should they be. That would merely degrade the quality and possibly cause other complications in the burning process.
I have no idea what X-discs are, and have never worried about this.
Two pass conversion will only happen if you are rendering video, and it is using Variable Bitrate. It will improve quality, but will also take twice as long.
MPEG audio is not part of the NTSC DVD standard, and in the now distant past, NTSC stand-alone DVD players had difficulty with it. The same is not true of PAL DVD players which have never had difficulty with mpeg audio. So if you live in a PAL country, there is no need to avoid it -- though it will produce files about the same size as Dolby dual channel stereo.
Mitchell has already given the hard and fast rule about maintaining the same field order throughout a project.
Changing MPEG settings in the burning module only applies if you either have inserted a VSP file into the burning timeline or else have unticked the 'Do not convert' box. If you have inserted a DVD-compliant mpeg-2 file into the burning module, there is no need to untick that box, and so the ability to change properties does not arise. Ditto re the General and Compression tabs under Options.
I guess I will just ask. 
