So, I currently have one rep. If I repped someone else, would my rep point go away or would it stay with me? And if it does go away, how much does it cost to rep someone else?
You don't lose any rep, rep is just there to show how much you contributed to the community with helpful things. If people use or like what you have done, they will usually rep you for it, depending on what it was.
Rep power is the maximum amount of rep that you can give out at one time, and there is a daily limit I believe.
You can get negative rep if you did something that maybe is offensive to the site or others, or if trades went bad on your part. (not exactly sure as I have never needed to -rep anyone.)
Okay let's see if I can rep you all for your helpful answers...sorry zxzero I could only give three at a time but have no fear I will get to you eventually. Thanks all of you!