Also how will this affect my CPU long term? My cpu's only have a simple fan on them they're not water cooled or anything :|
CPU mining has been removed from CGMiner as of a few releases ago. You can use an older version of CGMiner, or you can switch to BFGMiner instead.
https://github.com/luke-jr/bfgminer
From CGMiner README:
Q: What happened to CPU mining?
A: Being increasingly irrelevant for most users, and a maintenance issue, it is
no longer under active development and will not be supported. No binary builds
supporting CPU mining will be released. Virtually all remaining users of CPU
mining are as back ends for illegal botnets. The main reason cgminer is being
inappopriately tagged as a virus by antivirus software is due to the trojans
packaging a CPU mining capable version of it. There is no longer ANY CPU mining
code in cgminer. If you are mining bitcoin with CPU today, you are spending
1000x more in electricity costs than you are earning in bitcoin.