Ricky,
Can I use the TMCC Command bass with the DCS remote and the WIU App without the LCS Wi-Fi device?
Yes, you can. However, you would have to define your Legacy engines as TMCC engines. If you do not, they will start up but not move.
I am a bit confused when It said that the engine would not move.
That's because Legacy engines use Legacy speed commands, which the TMCC base cannot execute. Further, an SER2 module is also required because even a Legacy base cannot execute Legacy commands that come in via it's serial port. The SER2 module addresses that issue.
Using the TMCC base, will my Legacy or TMCC engine run and have sounds?
Yes, it will work as if you are using a Cab-1.
Also, I don’t understand the Legacy page. Will the legacy functions work without the LCS Wi-Fi device?
What it needs is not the LCS module, although that may also be present; it needs the SER2 module, See answers above.
The TIU must interface to the Legacy base via the SER2 module if Legacy features are desired. That's how the Legacy base is designed.