Re: interference from cordless phone - i think - can different a
The link I posted shows the signal strength and frequency range used by a Siemens 2.4GHz phone in operation right next to a 2.4GHz scanner.
Placed in close proximity, the phone would likely kill a WiFi connection for a data device in Channel 4 (2432MHz center frequency). Idealy, you would check the exact frequency of your phones (they probably span some portion of 2400-2484, but not all of it), then set your AP to the least conflicting channel. You may be able to restrict the channels that the phones use, but it's not likely unless you can tell them they are in another country (different regulations, different channels).
Since the phones use frequency hopping, they would be fairly tolerant of a strong WiFi signal (but don't put the AP in the center of a hallway where they'll walk under it while using the phones).
Even though Cisco 350 series PCMCIA cards have the same signal strength as the phones (100mW), using a high-gain antenna on the AP will help the users 'hear it' and help the AP 'hear' them over the phones. I would suggest a 9dBi or better patch placed inside an outside wall for up to 200 meters of range. They're less than $50, so it's a quick fix to get 500mW effective power.