I have not noticed a difference in duration yet. I have had this light for about 5 months now, I have used it maybe 10 times. BUT in my personal opinion, I think there would be an effect on the battery (like with any battery) but it would take years and would not be noticeable for a very long time even with regular use.
Not sure, I just put them on the windowsill and they are fully charged at night. BTW, I accidentally left one on and when I saw it in the morning, the LED was still emitting a faint light! Also, even the faintest light will charge these, they don't even need direct sunlight!
Hi! Just one. It is very bright though. If you hang it in a 12x12 room you will be able to see everything. Its bright enough to read by. Ive used it a lot already and really happy. I will be buying more when I can afford it