If you set a different channel/channel width as root AP, the connection between your root AP and your WA7210N will down, you can have a try on this. I guess the the channel/channel width option on...

Why not buy an USB to Ethernet adapter for your MacBook Air?:o

CPE210 doesn't support external antenna, TL-WA5210G can meet your requirements, you can attach your current antenna to TL-WA5210G via a type N to rp-SMA cable, it supports 11b&g while doesn't support...

You can choose wireless channel/bandwidth only in AP& AP router mode. In other modes including AP client router, its channel/bandwidth must follow root AP, no way to change it manually.

See below in line: What is maximum connecting capacity it can handle.? ie No wifi Client Machine i Mean. The maximum capacity number is around 15, but it still depends on the bandwidth requirement on...

Refer to: http://www.tp-link.com/en/faq-908.html. Besides, 24dBi is too high, it's usually used on outdoor access points other than indoor access points such as TL-WA801ND