Glad to hear you plan on quitting smoking soon! That's wonderful...

I would recommend a slow reduction in caffeine intake over the course of a few weeks. This will help prevent the withdrawal headache at least.
As for fatigue - I just rest whenever I can. I also try to eat 4 small meals spread out throughout the day filled with better for you food (lean protein, some fat, high fiber, & very little sugar) to keep energy up higher & prevent "crashes".
There are some here that will take a medication (Provigil) to help their energy, but I'm not sure how effective it is or if it's a good idea (because with lupus, you probably do NEED to rest when your body is telling you to rest). It's very expensive, but it's something you could ask your doctor about.