Hi!
With regards to the Maple Syrup, weighing it is much more accurate because difference syrups can have different densities. Measuring by liquid volume can therefore lead to inaccuracies with regards to how much sugar is actually being added.
With regards to solid rice - I do have flaked rice and rice hulls in the existing database. The flaked rice is the more popular brewing additive since it can be directly added to the mash. Is there another type of rice solid you are referring to?
The totals in the rating block are related to the BJCP score. You can check out the BJCP web site to see how the 50 point scale is determined. I was reluctant to do that in the program as the scoring system is copyrighted by BJCP.
Cheers!
Brad