To start redis with a config file all you need to do is specifiy the config file as an argument:
redis-server /root/config/redis.rb
Instead of using and killing PID's I would suggest creating an init script for your service
I would suggest taking a look at the Installing Redis more properly section of http://redis.io/topics/quickstart. It will walk you through setting up an init script with redis so you can just do something like service redis_server start
and service redis_server stop
to control your server.
I am not sure exactly what distro you are using, that article describes instructions for a Debian based distro. If you are are using a RHEL/Fedora distro let me know, I can provide you with instructions for the last couple of steps, the config file and most of the other steps will be the same.