>I have a report that will group by categories picked by the user by using the evaluate(pcgroupexpr) in the report form's data grouping properties dialog, but can you programmatically set the "Group starts on" the "New line" or "New Page" so it can be a selection the user can choose prior to running the report.

Take look at www.report-sculptor.com
Amongst other things it offer possibility to programmatically create reports. You can do it all in code, simillar to old style dos reporting
with ?/?? @..say eject etc. , but also as combination of visual report design with form containers which you then drive as report from within your code. Hence there is property that holds remainder of the page in pixels, which you can use to break pages as you wish
and show content according to your own criteria.

See samples in rsDemo project.

RS is completely free.

HTH
Sergio