Voltage, LAN, and Firewire. Help?

[LeoAlpha]

I have three basic questions.

1. Are the charger cables and cradle for my PDA and laptop compatible with international voltages, ie 220 as apposed to USA 170?

2. If my motherboard has LAN 10/100 do I need a separate wireless network adaptor, and where does ethernet come in?

3. If my motherboard has a firewire port, do I need a seperate firewire card, and where does it go, and what's the point?


Thanks.