For infrared communication, it looks like IR receivers (3 leads) are preferred over phototrasistors (2 leads, many look like LEDs). Why is this? Is it because the phototransistors are very directional?
May or may not be preferred. Many 3 wire ir recievers have a 38 k hz filter and demodulator going to a gate of some sort. Good for recieving digital data from a transmitter. Pick a part number and get a spec sheet.