Sorry guys, I'm just full of questions

Another project. I assembled and rendered as mpeg2 is 75 mov files totaling 5.6gb of space and 4:54 hrs of time. I tried the bitrate calculator and it seemed to say 1832 is the average bitrate to fit on disc, but go to DVDA and it won't let you because the bitrate is too low. So since I already have made one big mpeg file, is there a way to cut it in half and make 2 DVD's without going back and re-rendering in two pieces? And I still can't figure out the bitrate calc thinkg. See if someone gets the same numbers that I do on the above size and time.
Thanks guys, don't know what I'd do without this site & everyone's help!
Steve