In 3e this spell is called Create Undead. As of their intelligence and memories - rules do not say much as it is expected that they are created right away (possibly by another vampire, ...). In my realms it depends on time spent dead and they loose some of their memories for long time until they fade away and cannot be raised as higher undead anymore. Memories are lost by significance to the deceased so most important parts are kept longest. Time in this state depends on person's closeness to his diety and is about 200 years (time is relative on the Planes so it might be different if needed). It is easier and faster if they are closer fit to blend in. Some of the dead are chosen to be made planars in service of their diety and that is made right away and there is no chance of bringing the soul back except summoning the planar being.