Answer to: What is Tos02 on the board?The 10 "pads" are a connector solder pads: there is a connector P/N associated with them (J5101) and a little arrow to indicate pin 1. Looks like JTAG or some other debug connector to me. It was likely populated during development, but omitted for production.
Answer to: Is there internal microphone in the Apple TV 2nd Generation?There is definitively no microphone in ATV- no reason to justify the addition of an analog audio Codec in this box. If it were the case, there would also be an analog output (likely on a 3.5mm stereo jack). If video-chat was to be added, I would imagine that it would be through an accessory that would provide both video and audio capture, better located than ATV that may be hidden in a cabinet... This said, most webcams use the full USB power, or 500mA/5V, which is half the total power available... Not sure there is enough overhead for this...
Answer to: WiFi / Bluetooth AntennaYou will notice a trace on the main PCB coming out under the Panasonic board, and connected to the ground through a curved PCB trace with a couple of components (likely resistors, although I may be wrong here) - this is the antenna, directly etched on the PCB. It faces the front right corner of the device. The design is a 1x1 802.11n, with 150mbps max BW. The Boadcom IC supports shared antenna for BT/WLAN, so only one antenna is necessary (although there is no indication that BT is fully functional and the software stack available). We can imagine that the BT function will be enabled once accessories are available- nunchuck anyone? This is a bit different than the implementation from the iPad where two antennas are used, although they likely perform antenna switching, not diversity, leading to the same maximum bandwidth. The idea is to chose the antenna with the best reception, less at issue with ATV as the device will remain in a fixed location. The likely reason for Apple to use a Panasonic board instead of...