RIOT-OS and multiple executables

I am brand new to embedded programming and am wondering if RIOT-OS has the capabilities that my small project requires.

I have 3 executables, *fizz*, *buzz* and *foo*. They all do separate - but very important - things. My understanding with real-time OSes is that you typically:

1. Take your app’s source code and somehow merge/splice it with the RTOSes source code; then 2. You cross-compile this conglomerated source code (again your app + RTOS source) into a binary that is compatible with the ultimate platform/architecture you will run it on; then 3. You flash the binary to the chip using something like UART or SPI, etc.

My first question is: is this understanding correct? If not, can you please help me make a quick course correction?

Then, as a similarly-related followup, I’m wondering if RIOT-OS supports the concept of multiple executables running when the chip/OS start up? In other words, is it possible for RIOT-OS to be cross-compiled with, and then at runtime execute, all 3 executables (fizz, buzz and foo)?

Thanks! Zac