The antenna connected via a cable, with one with the small mag mount at the bottom, is for receiving transponders, Mode S with or without ADS-B, and is connected into the DVB-T (small black square) dongle. The other antenna with the 90 degree bend and the SMA screw on plug is for the P3i, which is the inter-PilotAware communications antenna, for transmitting and receiving the unit's position to/from other PilotAware units. Do not switch on the unit without this antenna connected or it could damage it.
The power cable is micro USB, and you really want one with 20 AWG power conductors in it.