Well they're not too keen on being pruned - the best time is June. I wouldn't advise cutting it back now - its too late in the year and any new growth forced by the cutting won't have time to harden off before winter.

Certainly not now as the flower buds are forming for next year (I noticed tiny little swellings on mine at the weekend)
Wait until the flowers have all dropped and just tidy up any straggling stems.

I feel the need to explain my 'prune in June' advice - make it early June, after the flowers have gone, and you can reduce the wood by up to a third if you want to. There's a risk, but I've done it 5 times on different plants and its always been fine - but maybe I'm just lucky! Unlikely to flower the following year if you do prune by that much.