2. Yes, you can split one big program into smaller programs. But I'm sure that a DVD recorder has an option to set the length of time (e.g. 5 minutes) a chapter is to be created.
3. You have to burn to a new blank DVD.
DvdReMake is an editing program, not a burning program, so you have to use other burning software to burn the exported DVD to disc.
Menu options and abbreviations are explained in the manual.