Are there any specific rules about how property can be disposed of?

In general, the answer is yes, but if (for example) you indicated that all your effects should be buried in a big hole in the back of your property, that request might be deemed inappropriate by the courts and denied. A judge can void all or part of a will. You cannot change the effects of law just by stating your wishes in your will. For example, you may not suspend or terminate any legal rights or claims that a spouse, child or business relationship may rightfully have against an estate just by stating that in a will.  They will remain in effect.