Migs half way there, they are crap. They have an amplifier built into the base of the ariel and after years of water and crap getting in there they give up. Mine was £50 fitted at a local radio place, sure you could pick them up cheaper and fit it yourself, but i have been told its an arse to get the old ones off.
As for the permanent live swap the yellow and red cables on your harness adaptor round and your away.
Hope this helps.