Ok here is a link to a good stress test. https://www.overclock.net/attachments/13202
Then you want to download HWINFO64. It's free and is the best monitoring software for FX.
There is a good overclocking guide around here somewhere that I can not find. Maybe someone else knows where it is.
Yes your voltage will fluctuate depending on use as that is the power saving feature in action. You will want to disable that and a few other things when you actually start to OC.