Please do not breed your turtles. Turtles are already overpopulated as it is, and many are in foster care because their owners couldn't take care of them, and many many more have been euthanized because of the overpopulation.
RES are considered an invasive species in almost all states and countries, and irresponsible people release them in the wild. RES can completely destroy a local ecosystem in a matter of months. Many places will euthanize any RES caught outside. Ask zoologist, she's had to put down quite a few, and hybrids (as you are proposing to breed) are also put down. It will also taint the genetic pool, meaning that if too many hybrids escape to the wild and successfully breed there, someday (maybe not in your lifetime, but soon enough) we won't have two separate breeds and only hybrids will exist. That means that RES and YBS would be extinct for our children ...
Also, turtles can lay eggs as often as once a month, for like thirty years. That's 360 cycles of eggs. They can lay as many as 20 eggs per clutch. That's 7200 eggs over a lifetime. Assuming they all hatch, at 100 gallons per turtle needed, that's 720,000 gallons needed to care for the turtles from one female, never mind that 50% of the 7200 turtles produced would be female, creating more eggs ...
Yes, baby turtles are cute. Yes, baby turtles grow up to be big turtles pretty quickly. Please, if you want additional turtles, adopt. Trust me, it's not hard to find shelters with turtles ...
http://www.azgfd.gov/w_c/nonnativeturtles.shtml