It's up to the person who gives it to you to decide to put their user name in the comment.
If the person doesn't put their user name there it is less likely the system would get abused, in my opinion.
Wtp… I keep getting beaten. .o.'
Mods and up are the only people able to see who gives them rep for the above reasons.
If you see that someone is abusing your reputation, then you can just tell a staff member and we'll see what we can do about it. So it's not all a bad thing.
Red is bad rep. Grey is neutral, and Green is good.
I thought grey meant they wanted to bad rep or good rep you, but didn't have enough rep altering power to do so.
Well, I went to give a rep to someone, and there are only two options,
"I agree"
"I disagree"
Yes, that's what I meant. You can either good rep a person or bad rep them. But the amount of good rep or bad rep that you give depends on your rep altering power.
So, if people who have a rep altering power of 0 try to rep you, you won't get any actual rep added or taken from you.