The amount of energy you can harvest is very, very, very tiny so don't expect great results.
1. If you know the frequency you can optimize the antenna by making it resonant. Wide band will probably give the poorest results but it depends on individual situations.
2. To get any appreciable power you either have to be in a very strong signal area or use an optimized antenna.
3. Yes, but the signals from the array need to be in phase and this would be extremely difficult, especially if you use a wide frequency range.
4. Power out can not be greater than power in - so the answer is no.
5. 1N34 is a small signal diode and not intended to be used as a power rectifier. Don't forget that a bridge drops twice the voltage of a single diode so you will get even less voltage out.
In summary, it will work but think in terms of getting enough power to light an LED and not even very brightly, and even that depends on you being in a high field strength area.
Brian.