All of the above, but....
The worst time to ride in the wet is when is just started raining.
The road surface will have derbies, rubber, oil etc lying on the surface after a dry period. It takes a while for this crap to be washed away leaving a reasonably grippy surface, so take it very easy for the first 30 mins of any downpour, after that its fairly safe to ride pretty much the same as you do in the dry, avoiding the very very slippy bits such as manholes, overbanding, white line, leaves etc.
Lastly dont ride on 'A' point of the road (the middle of where car tyres have not been) as this is where all the crap lies, ride in the postion where the offside tyres of cars run as this will be where the best grip is (applies to the dry also), it also give you advanced views for better planning of whats happening ahead and a greater margin of safety if some twat does something stupid in front of you.
Well thats what we in the old bill do, ignore our advice at your peril :violin:
Buzz