"Walkers, Biters, Zombies, Lurkers, Roamers, Geeks"
Compiled is a list of things your character may or may not know yet. Act accordingly.
PHYSICALITY: Walkers have basic motor functions and physical skills. They can walk, push, pull, climb, claw, grab, groan, and bite. They can smell, hear, see, feel, and taste. What they cannot do... is run, jump, open doors, swim, talk, use weapons or devices, understand words, convey emotions, or do a sudoku. While they are still able to carry out basic functions, their reaction time is severely decreased. However, they are incredibly strong and determined to do whatever it takes to get what they want. They have absolute pain tolerance and won't stop chasing something until they are distracted by another object, or killed.
SOUND: Everything from a gunshot to the sound of somebody whispering. A walker's hearing is just as good as, if not better than, a normal person's. When they hear something, they will immediately stop whatever they were doing and gravitate towards that noise. Talk about ADHD.
PEOPLE: Walkers are like me: all they care about is eating. Unlike traditional zombies, walkers aren't only after brains. They'll eat the body of and drink the blood of animals AND people whether they are alive or dead. Blood and guts, therefore, can be used as a wonderful piece of bait to lure the attention of walkers... (if you don't mind getting your hands dirty). However, the rotten smell of dead or decaying flesh isn't something walkers are attracted to. The smell, in fact, acts as a repellent if one were to cover themselves in it. This would make them otherwise undetectable by the walkers unless said person started acting suspiciously enough for the walkers to take notice.
WEAKNESSES: The only tried and tested method of killing a walker is by severely damaging or destroying their brain. A walker's decapitated head could still be alive and functioning if the brain is still in one piece. This isn't too difficult to accomplish since they are slower, and less agile/coordinated than we are. They are easily distracted, often walking away from whatever attracted them in the first place for something more favorable. They can die from starvation if they don't eat enough.
STRENGTHS: As mentioned before, the walkers are a determined bunch. They will stop at nothing to get what they want. They will claw and bite their way through doors and metal objects, regardless of the pain. They will come at you with everything they've got until they are killed. They are most dangerous in groups, but easily dispatched when alone or in small numbers. Walkers are extremely resistant to extreme weather conditions, but their muscles are still affected by the cold. They do not need a functioning heart or even enough oxygen to keep the brain active, meaning they can both breathe underwater AND sustain significant fire damage until their brain is destroyed.
INFECTION: The infection is only spread through bodily fluids. A walker's blood or saliva would have to make its way into a person's bloodstream for the infection to take hold. The person would then have anywhere from 1-10 hours before they died and came back as a walker. Once infected, the person would experience a increasingly deteriorating physical and mental state in which they would suffer extreme cold and flu-like symptoms, including: a heightened temperature, chills, coughing, nausea, dizziness, blurred vision, diarrhea, cramping, muscle tension, dry mouth, red eyes, insomnia, hallucinations, and violent hunger pains. Eventually the person's temperature would get to a point where they died, and they would come back as a walker within 1-10 minutes. The only known way to stop the infection is to amputate the bitten body part within the first minute or so of infection, before it has time to spread through the bloodstream.
For a more detailed explanation, visit:
http://walkingdead.wikia.com/wiki/Zombies