How to setup a Wireless Access-Point using my laptop's WiFi card?
Not all wireless cards support Access Point mode. Check to make sure your card does, before you frustrate yourself in software.
OpenWRT uses hostapd to provide its services. It is available for Utuntu.
You will need to arrange for masquerading and firewalling as well. I like Shorewall for things like that. In your case the two-interface model should work well.