recordingto 650 or 700 MB discs
 

Let's say I want to record 650 MB of data to both 650 and 700 MB discs. The 650 MB of data will obviously fill up the 650 MB disc, but what about the 700 MB disc? Will it be stored in the first 650 MB leaving the remaining 50 MB free (on the outer fringes), or will the first 50 MB be left free and the next 650 MB used?

Another question: Will one year old home or car MP3 players have a problem with reading the 700 MB discs, because the data tracks are closer to each other and therefore do not follow the CD Red Book Standard?

found that Hi-Fi's any brand over 5 years old can't really read
700MB audio, off and on though hardware dependant, 650MB
4 audio RLZ.

Man, if u know about track width, u should already know that
CD's are written from the centre out, you can always make
50MB of silence for track 1 so that the other tracks play better
as the more centre tracks are likely to have write problems,
whilst the outer edge tracks wear down quicker due to wear
and tear.