quick questions i got about it

1. can i use my radio to make it so each stick runs each tread, it says this thing combines them into one?

2. very noobish question what is this? Receiver battery eliminator circuit (BEC) standard, does it take the battery for the motors and puts it to the reciever at a safe voltage?

3. anything cheeper seems like your paying more for the 2 in 1 thing

thanks for your help!