In Search: Unnecessary number of filter options

there's an unnecessary amount of filtering options under search. I guess its okay to show the options available, but for several tags there are multiple filters without any hits - why are these shown? The number of filters is already many, some of them with descriptions not too accurate (but I guess they are for some people...) 

This is mainly for trying to remove some noise from the filtering functions.  

An explanatory information document for the filter options would also be nice. many people who will be trying to filter will really struggle to know what to filter on.

Can hide properties from filter if none of the values are populated.