I've had herpes occassionally on my lips & nose for about 15 years. Now I'm taking Famvir (novartis) when I have the first symptoms, will it cure it forever?

No cure. Herpes unfortunately won't go away. You are likely to have intermittent outbreaks indefinitely. Try to id a pattern to the outbreaks. Occasionally a precipitating cause can be id'd and avoidance prevents another.
No. The virus can't be "killed" in the same way that a bacteria is killed by an antibiotic. But the antiviral medication can "suppress" the virus to prevent or lessen the intensity of an outbreak. Once infected with these viruses, they live and continue to reside in parts of the nervous system, but may stay in a dormant or inactive state. The virus is subject to reactivation by various things.
Unlikely. Currently, there is no medicine that cures herpes simplex infection. Taking the medicine may shorten the duration of your flare ups, and can be used to prevent new flares, but even on medicine, you can occasionally have outbreaks.