Thank you @ludwig_bre@Jesserosco for your help. You certainly raised my IQ by few more points : D
I am all set, I tested the steering servo with external battery and worked perfect, so I went ahead and ordered 5v step down BEC to finalize the setup.
Edit: Yes at some point I plan to build the differential speed similar to @Jesserosco if my Aliexpress Fly color X ESCs parts arrive in this life time