I think you are over thinking things.
Giving rep does not effect how much rep you have. To give rep has no effect on your own rep whatsoever.
The amount of rep you can give and take away is determined by the number of poss you have. I think rep power goes up 1 point every 2000 posts. (Not to certain but something like this)
After you give out rep to someone you cannot rep them again for a while. This stops people abusing rep. For example, people could just continuously rep their friends, this sort of defeats the purpose of rep as it was gained unfairly. So to stop this, you must rep a certain number of different people before you can rep that person again. Furthermore, to stop you from spreading too much rep in one day to rep your friend again, there is another rule where you cannot give out any more rep for a while because you have given out too much reputation in the past 24 hours. So really these rules are in place to stop people abusing the system.