The lines in the config file do the following

These lines tell the client where you have Boinc Installed and where your Boinc data files are stored. They are important if you installed boinc to a non-standard location.
boincdatadir=
boincappdir=

These lines tell the client your authetication details for your boinc projects to access and validate your Research Credit statistics:
email=
boincpassword=
boincusername=

This is your public cross-project unique identifier that links all of your research projects:
PrimaryCPID=

These are the default Gridcoin blockchain nodes:
addnode=node.gridcoin.us
addnode=gridcoin.asia
addnode=grcmagnitude.com

These are options that can be set in the client gui for various misc options:
UpdatingLeaderboard=false
enablespeech=false
poolmining=false
suppressupgrade=false

Once you are up and running this file will also contain your blockchain Public and Private keys so is very important to back-up and keep secure.