CDs are, of course, limited to 44.1khz, 16-bit audio.  There’s a maximum of 99 tracks on a CD, a maximum length of 79 minutes (most top out at 74), and the minimum track length is 4 seconds (including a 2-second track pause).  The pause before the first track must be 2 seconds, although subsequent tracks may not need to have any pauses at all.