RE: Can I plug a 7.4 lipo directly into a receiver?
You either need to connect a micro ESC with BEC to the system or you ahve to use a power regulator. Power regulators are large and are made for giant scale planes where size is not a concern. Do not plug a LiPo directly into the receiver.
If you can find a micro transformer or regulator, use it, if not the Micro ESC will do the job well.