Connectors on Device prototyping
There are plenty of places on the internet where you can find pre-made libraries:

http://www.element14.com/community/community/cadsoft_eagle/eagle_cad_libraries
https://github.com/sparkfun/SparkFun-Eagle-Libraries
https://github.com/adafruit/Adafruit-Eagle-Library
http://www.we-online.com/web/en/electronic_components/toolbox_pbs/Eagle_eiCan.php

I simply googled "Eagle Libraries" and got the above as the top four hits.

Generally, I recommend making your own custom libraries for consistency sake, but that's just my own personal preference.

Some of the parts you describe are far too specific and will probably not be found in a pre-made library. You'll need to select the part using Digikey or Mouser and view the datasheet. Use the information in the datasheet to create the component in a custom library.

Your wording of your last question is not clear. It does not seem to have anything to do with Eagle or PCB design, but rather the software on the microcontroller itself, which should be asked as a separate question.