well that's about 1000 questions rolled into one but i'll do my best
plums: are you training the plant or is it already established? prune to train early summer, prune older trees at the end of summer and just remove dead and deasesed wood along with branches which are rubbing against each other.
loganberry/tayberry/blackberries and autum fruiting raspberries: cut down the canes which have fruited once they die back, tie in new canes for next years crop.
summer rasps: cut once the fruit has been picked.
gooseberries and white/red currants: winter, cut back the years growth by half on main branches and to about 2 in on side shoots, remove dead deasesed wood. you can trim back the side shoots again in june if it's looking too bushy.
blackcurrants: once the bush is established 3-4 years, you want to take about 1/4-1/3 of the oldest wood out each year while maintaining an open plant (a wine glass shape).
general rules/good practice. don't prune in the rain/high humidity as this increases the chance of infection. remove anything which is dead or ill and burn it. when cutting the branch take it back to just above a node so that there isn't a big chunk of dead wood on the plant and make the cut at an angle so water can run off the cut rather than sit and rot it.