Passive Component ratings displayed on schematic - Use actual value or design requirement value?
My usual practise is to place actual purchasable values on the parts in the schematic with (where appropriate) a note giving any relevant formula. There are usually less then 5% of the parts where there is enough maths to matter. 

This is kind of important if the assembly BOM is to be exported from the CAD tools (And you REALLY want BOM generation to be a fully automatic thing), nothing worse then having to hand hack a BOM (Except possibly hand hacking the XY placement data!). 

My libraries are set up so that there are distinct libs for 0402/0603/0805/1206 parts which means the layout guys get the footprints from the schematic database.

In terms of the amount of data to include in a component, for jellybean stuff I usually give values, power/voltage ratings and package details, maybe dielectric, but leave the manufacturer as generic. Then in my BOM template I list acceptable vendors for the generic parts, "Or equal and approved" is a key phrase as it means you will be asked when they want to sub something insane.  

Generally, while all this metadata is there, I turn off things like power rating and dielectric in the default view, folks can get them if they need to know, but it is not helpful for 90% of the reasons people look at a schematic ("4k7" is helpful, "4k7,1%,0.063W,0603,50V,Thick film,Vishay Dale" is just noise most of the time). 

Like everything else in this game, the right answers here probably vary depending on what you are drawing and who the audience is.