The same as with wireless G card and G router.
Yes.
Yes.
Yes, you can. Wireless N devices are reversely compatible with G networks.
A Wireless G router provides Wireless access to 802.11g compatible devices
Yes, it will. It will work with A, B, G, and N standards.
Yes. It will not have the same performance as a N receiver, but they will connect and work.
Yes it is backwards compatible
If you have free PCI ports then any (but your router supports for instance only wireless G it's better to buy PCI card with wireless G support and not less).
No they do not. They simply have to work on a compatible frequency. Such as wireless a, b, g etc.
A wireless router "N" has one of the fastest speeds available. It is more costly than the basic wireless router speed of "G". To ensure getting the fastest speed, be sure both the wireless router and wireless card have the same speed. Most laptops with built in wireless cards only have a speed of "G". The network runs at the slowest speed that is being used. An upgraded card may be needed.
No.
Usually they are, you have configure the router for G wireless networks.