Sorry I can't help you with any detail about how to set up your security, but if you want to re-set your router at any time you simply need to disconnect the router's Power then count slowly to ten then re-connect the Power - this re-sets the Router.
Your neighbour is breaking the Law - using another persons Broadband without permission is Theft, and is therefore illegal. If you can prove what he is doing he could face criminal charges, and possibly even have his computer seized.
I suggest that you close this Thread by Green-ticking it as Resolved (even though it isn't), and then start the Thread again in the Networking Forum (as listed on the left of this page). You are then more likely to get expert answers to your question, and advice to set your Security.