When fired point blank, plastic BBs can hurt as much as rubber bullets, however most people engaging in military simulations with airsoft guns wear thick military garb. Additionally, precautions are taken to protect the neck, face, and eyes. Many people chose to wear a balaclava around their face and neck and lithium battery stocks ANSI approved eye protect is a must. The only place that plastic BBs can really cause damage is to your eyes.
The battery will over-charge if left attached to the charger. The battery stops charging automatically when full lithium facts so it will not over charge. If the battery is left on charge too long it is possible that heat will damage the battery.
I spent a few days looking over the internet for a decent camera that would fit an amateur photographer like myself. I decided to go with the Canon EOS 1000D.
The iPod warranty is one year but you can expand it for two years with AppleCare Protection Plan for iPod. Various merchants have inexpensive extended warranty coverage available and often these programs purely change the lithium bettery stock product with a corresponding new unit.
Briefly relating back to overall size... many lithium 18650's will differ ever so slightly in length (measured in millimeters). This is mainly due to an added protection circuit. The circuit helps to prevent the battery from over-discharging, since Li-ion cells can easily become damaged if their power is drained below a particular voltage. The protection circuit also prevents the cell from being over-CHARGED as well. These cells are very sensitive. They must be handled carefully, gently, and as described above, must never run-down too far, or be charged over and above their threshold. They can actually explode if severely mistreated!
The bottom line, be gentle to your lithium-ion batteries. If you excessively charge the battery, with high voltages, and heavy load conditions, it will shorten your battery's life. It's best to charge at a slower rate.