I have ESCs with mode Linear; can I use them for my motors? Answered

I recently bought 4 ESCs for my 4 brushless motors. THe ESCs are 20Amps. However, I found out that they have BEC mode linear and I might need an external BEC to power my receiver.

Now my question is; lets say I am not using a receiver, I am using xBee mdules, which are going to be powered by arduino. Do I still need the BEC? Also, how would I power the arduino which needs 5Volts. Do I put a seperate battery for it?