The radio wire will be the receiver aerial. On AM and FM outfits, this is usually the long piece of wire hanging out of the receiver normally at the opposite end to the slots where the servos plug in. The current crop of modern 2,4GHz sets have a much shorter aerial, the only important requirement is that it should be above water.
Sail servos come in two basic types - some have a very obvious battery connection lead and supply power to the receiver down the lead that plugs into the receiver, the rest are powered from whatever is powering the receiver. I suspect that yours is the latter. The receiver battery plugs into the receiver in the slot (usually with just 2 pins) market "Batt".
Some 2.4GHz sets have many more channels, and assume that power will feed from one of the peripherals, so do not have a dedicated battery slot.
should be is no need at all to get out the soldering iron or do any dismantling of the servo.