Lofoten Islands, when best etc

Hi, am planning to do this later next year, ideally seeing the NL too. I'm toying with when is best. Had best NL ever when there in mid Sept, walking. I wonder how much earlier one can go and still see them. Is there a mozzie issue there as on the mainland? Nothing in early/mid Sept - but dare I go earlier? How much earlier to still see the northern lights?

For info, the loose plan is to start at Bodo and end at Narvik (or the other way round?), but lots of research to do first... For instance, it might be best to head back to Bodo and re-use the bike box, but what's the score with bikes on buses? This would leave us the option of dumping walking gear there, maybe for a quick wander into the hills before heading home. But if we did this, I suspect Narvik might be a better start, better access to mountains?

Also, are there any good bike shops in Bodo and Narvik? Could then dump the box used on the outward journey and acquire another for the return journey from the other town.

Thanks,

Rob