It depends how well its yielded, you can get the buds off without damaging the plant and it'll regrow in soontime... but if you fuck them up or damage all the "branches" or whatever you'd better start germinating more seeds. its pretty easy to get the buds, just read some websites on growing/pruning and you should be set.
You can take cuttings off a mother plant and just have clones flower to keep the mother plant in vegetative for longer or whatever. Check out this site...it explains it. http://www.overgrow.com/iss3/mums.html
Yes you can . You can do it up to 3 times . After that its not worth doing cause the yeild will be so little . Every time you re-veg and re-flower them the yield decreases noticable . I do know what im talking about since ive read almost the whole grow faq at www.overgrow.com . Go their for all your growing needs .