Actually no. As jeff said, most AP's do not support dhcp, most APs simply sit on the lan and passes through this information once the client authenticates to the AP. And for all intensive purpose, whether he installed an actual "ap" or a router with an integrated "wireless ap", it does not matter; as long as it is configured properley.
As far as signal is concerned, if you are going to amplify with some sort of antenna, you dont want a yagi or paddle in this instance. Those are typically used for directional communications and in your instance youre going to want something classified as "omnidirectional".
However, all that being said. If youre not getting signal 10' feet away there is something else going on and amplifying the signal may only make it worse.
Troubleshooting wireless is a far more difficult task. For instance, a common problem, is multi-path return to the AP. In other words the signal is so strong its bouncing off all the walls and creating multiple paths between the AP and client; so in some case, throttling down the power increases performance. But without a very expensive "spectrum analyzer" all this is simply conjecture.
good luck.
