First of all, you need to tell what ipod nano it is, the new or the old??
All ipods have the same type charger so any ipod charger will work with any ipod
Not all iPod speakers and docks work with all iPods, so it's best to check before you buy. Most speakers come with a number of plastic clips though which help you connect most models to most speakers. A lot of stores do have a list, often hidden within the specs, of which devices and generations of those devices the speaker plays with and it's definitley worth having a look as you don't want to get home and find that your iPod or iPhone is the one that isn't compatible. But of you ckeck often there are updates that could help.
All iPod chargers work with all iPods.
The best speakers you can get for your iPod is a debatable topic, for all opinions differ. The best in the market currently is the "Logitech S715i" for around $125, or the "Altec Lansing Octiv 650" for around $175.
Apple makes all iPods. If it is not made by Apple it's not an iPod.
All generations of iPod Touch have WiFi. No other iPods do.
yes all ipods work with ipod docks All iPods with the female slot at the bottom (not firewire ports) can be attached to docks and so forth. Firewire iPods can only connect via the sound port (head phone jack) and the firewire port. If a dock does not have one of these, it will not work with that iPod.
I guess not any speakers. The function of skipping songs with your headphones will be unable to use since you don't have a button to skip your song with.. So the downside of this ipod in combination with speakers is that you can't decide what song you want to hear or don't want to hear.. The only thing you can switch with is the shuffle option and the play option.
Yes. it works for all ipods.
yes all ipods are music sharing compatible
Well it all depends on what ipod you have/get. All 3rd generation ipods excluding ipod shuffle will be able to store videos on them and be able to watch them. On the 2nd and 1st generation you cannot watch them but you are still not able to store them on the ipod either.