How much video & audio bitrate do I need for dvd videos? I have videos with ~5000 kbps of avg. bitrate, if I burn the videos to a PAL DVD, which the resolution is low...(720x576), with 1000 avg. bitrate, will it be obvious to see the difference in quality? If so, can you suggest how much bitrate do I need in a dvd video? I prefer better quality and lower in size. Since the ratio of PAL DVD is 1.25, but the videos' ratio is 1.7 (originally 1080p), will the side being cropped or shrinked until it fit the width? (First time trying :D) 
Let say if this is my TV's size, exactly 720x576 :



And also, how much audio bitrate do I need (normally I use AAC 128 kbps when watching on pc)? Some video's audio codec is 16-bit, 2 channel FLAC, is it recommended using FLAC instead of AAC in dvd?
Thanks.
More than 'what do I need', you should ask yourself 'how much am I allowed'.

This page mentions an average bitrate of 4-5 Mbits/s, this is audio + video + subtitles. It also depends on the length of your content (as you also have a maximum capacity of about 4.7 Gb for a single layer DVD-Video).

FLAC is not supported on DVD-Video, common audio codecs are MPEG1-L2 and ac3.