1966 Radio Install

[LovinMy66]

I have an aftermarket radio that fits into the factory radio slot (god forbid anybody hack that up!). Anyway, I've heard the best way to do this is to hook the power wire up to the break lights wire. The reason for this is so the radio always has power (memorized station presets always preset.) here are some questions i need help with.

1) There is an Orange Wire all by itself and the tag reads "+12v for automatic ariel. 500m?? Max" ?? = faded off - What is this wire for?

2) Theres a 2 piece circle connector with 5 wires on it (Green, Black, Black, Red, Grey) What are these wires?

3) The radio has 2 RCA outputs.. Is it possible to hookup an AMP to this?

Thankyou so very much for any information. All this info would have cost me $45 from Circuit City!