As for the NAS (Network attached storage) I would hold off. I would either spend the money on a dedicated (used) laptop or use your current computer until you have an idea of how much storage you will be needing.
I need NAS for other reasons and plan to purchase 2-3 TB so I thought it could also be used in conjunction with the cameras, thus killing two birds with the same stone. Using a dedicated PC is not my preferred choice, but I already have numerous computers (laptops, desktops, and a server) available should I decide to use one of them for the security system.
These type of signs, while humorous and might deter someone, could also be a problem for the owner. If you ever did have to shoot someone in self-defense, the signs could be used as evidence as to your intent in a prosecution against you. I would not use any of these type of signs.
I would not actually use that kind of sign and only posted them in jest. For that matter, shooting an intruder would be my very last course of action, which is why I'm going to such great lengths to secure the perimeter, thus giving myself more time (advanced warning) so I'm hopefully not forced to make that fateful decision.
My security plans could be summed up in the following order...