If there is a big decoration hanging from the schach, is it OK as long as the top (part, or most of the decoration) is within 4 tefachim, or must the entire thing be within the 4? For example, the 2-foot-tall inflatable Chile pepper we like to hang. :)
Also, what about a paper chain? Certainly part of it is within 4, but if it is sufficiently long enough, it could dip down too low in the middle. (Trust me. :P) Is this a problem?