Hi waki! I have a large rosemary bush, and I just whack it back cruelly every few months when it threatens to take over. Up here in temperate Seattle, rosemary grows like crazy, and I've never managed to do much damage to it. It's worth noting, though, that the thick woody branches are unlikely to send out new side branches. I generally prune those back to their origin.

If the center is very woody and you're bent on having a really pretty ornamental rosemary plant, you may need to start again with cuttings next summer. If you're just interested in the culinary aspects, I'd say cut it back by a third, then cut it again after it flowers, and keep pruning it more often than you have been. In my experience, these are not fragile little plants. They don't like cold, though, so you may wish to wait until spring to prune so you don't overstress the plant.

As far as grapes go, my own grape vines are tiny little things that I put in just a few months ago, so I don't have any pruning experience. But I understand that the grapes flower from shoots on the previous year's wood, so pruning back too much of that could reduce next summer's crop.

My best advice is to get in touch with your nearest university and find out if they have an agricultural extension program. Our local ag extension program is amazingly useful and has all sorts of good tips for selecting and growing plants in our particular climate.