Dear Experts,

My two computers use Cable for internet connection via a switch.
Current Connection Speed is 100.0Mbps

I am planning to let the third PC in basement use Wireless to share the
access with those two systems on the second floor.

My little networking knowledge tells me that I need an Access Point and
a Client USB Adapter.

Questions:
1. The salesman recommended me to get both AP and Client in 54Mbps
instead of 108Mbps because he found that the internet connection is
just 1Mbps why get 108Mbps. Is it true? My PC shows 100Mbps connection
speed though. After setting up AP and Client in 54Mbps.. can my three
computers still have 100Mbps connection speed?

2. Can my two exisitng computers still connect to the ports in Access
Point via their original cables/wires, and just have the third PC go
wireless (USB Adapter)? Is this idea workable?
[2 pc's with cable connection and 1 pc with wireless connection?]

Thank you very much!
Ching