Question: Update time... I'm assuming that I should just
go ahead update both packages whether they are needed or
not... (assuming the update system will figure that out).

Or should I keep separate '%{version}-%{release}'
for each package??

Again... Thank you very much for all the guidance!

Keep them in sync. It's safer (so you don't forget to update one when the other requires a new feature from it).

The only really good reason to do otherwise would be something like a data set for a videogame where you probably don't want to force people to re-download hundreds of megs for every code change.