There's no way we can answer that for you, it's something you have to decide for yourself! You may as well ask 'is it worth having a car' or 'is it worth getting up in the mornings'
Yes, there will be quite a bit of work involved with filling, sanding, and painting. No, it will not add to the value of the car (if done poorly, it may detract from the value). But if it looks better to you, then it's worth it!
Only if your current wheels extend past the arches.
I love the fact I can squeeze through London traffic gaps with ease, if I had those arches I would have to wait in the queue!
Pete