Yes it has an external detachable antenae.
Yes it does come with a CD to help you.
For support for the WMP54G, go to the Linksys online community. They will be able to help you with set-up, update, configuration, connection and more.
Quick answer; no.Slightly longer answer; purchasing a wireless router or gateway will only allow you to pick up that particular router and whatever you have plugged into it i.e. DSL. Buying a wireless router will not enhance your systems ability to receive other wireless networks in your area. However, this can be accomplished by purchasing a wireless notebook card for a laptop, or a wireless USB or a wireless PCI card for a desktop. (The USB will work in both laptops and desktops)Wireless notebook card: http://www.amazon.com/Linksys-WPC54G-Wireless-G-Notebook-Adapter/dp/B00007KDVK/ref=xarw?pf_rd_p=237006501&pf_rd_s=center-10&pf_rd_t=101&pf_rd_i=598262&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0WS14WPQZ2VM6B4433V6Wireless USB unit:http://www.amazon.com/Linksys-WUSB54GC-Compact-Wireless-G-Adapter/dp/B000CRFI8A/ref=sr_1_3?ie=UTF8&s=electronics&qid=1214766739&sr=1-3Wireless PCI card: http://www.amazon.com/Linksys-Wireless-G-PCI-Card-WMP54G/dp/B0002LHSKW/ref=sr_1_8?ie=UTF8&s=electronics&qid=1214766787&sr=1-8