Practical Electronic Packaging - Definitive Manual Needed

Hello Everybody:
I am an electronics engineer. While I know quite a lot about
electronics and embedded software I feel that I am quite clueless
about the the mechanical aspects - things like nuts, washers, water
proofing of enclosures.

Is there a definitive reference for the practical mechanical packaging
aspects of electronics? Such a reference would address issues like

- where it is possible use plastic screws instead of mechanical screws
- what the heck do washers actually do (as I mentioned earlier I am
quite clueless)
- why do screws have different types of heads - phillips, straight and
all those weird shapes

- how does rubber tubing water proof an enclosure, what kind can be
used
- how does plastic hold up to UV radiation
- is it possible to get a RF shielding plastic

Any help would be appreciated. I looked all over Amazon but could not
find anything.

Thanks
Sanjay