Question: DVDFlick Help (Anyone That Uses DVDFlick)

Ok so I just updated my dvdflick to the current version of 1.3.0.4 Build 726 and I was just wondering a couple things. First is under the project settings/video/advanced i was wondering what DC precision does/means.

2nd in the audio options where you select the channel count, if i have a video source with a 2 channel audio am i still able to convert it to a 5.1. On the older version there was a small checkbox that said upmix stereo/mono to 5.1. Im guessing that if I just select the 5.1 in the new version it will upmix it to the 5.1 from a 2channel audio source.

3rd Is there a option to do the second pass encode or is the newer version that much better where you dont need the 2pass encode option.

4th In the general tab by the box labeled (use the MPLEX instead of TCMPLEX) what is that and whats it all about.

Thanks I know this is quite a bit of questions but I just updated from the old version and I would like to know about all of these so i can get the best possible quality for my dvd's. Thanks in advance for any help anyone can bring me.