There are several limits in place to what you can achieve with editing, bounties and voting:
You only gain 2 points reputation per suggested edit, once accepted. Moreover, this is capped at 1000 points, and your edits are reviewed first. On Stack Overflow, you thus need to convince 3 reviewers that each of your edits is good enough to be applied. You yourself already know what happens if too many of your edits are rejected; trivial edits are not enough.
Once you reach 2k reputation you can edit at will, and any edits you make will not gain you any reputation. People with more than 2k reputation making edits are thus doing it to improve the site.
Bounties cost the giver reputation, and you have to wait 24 hours before you are allowed to award the bounty to anyone. This is a great deterrent against gaming the system to 'gift' reputation to a friend.
A daily-run script detects serial up- or down-voting; if person A votes up several posts by person B, chances are these votes are going to be reverted automatically when the script runs.
The community has a very dim view of anyone gaming the system. If you see any specific gaming going on, please flag one of the posts involved and notify the moderators. They can then investigate and apply sanctions, if necessary.
For bounty gaming, for example, if you see someone giving multiple bounties to someone else, especially if the answers to which the bounties have been awarded are sub-par, please do flag one of those answers and use the 'other' field to explain what you have found.
In the end though, you gain reputation on these sites by providing helpful answers; it's how I gained mine on Stack Overflow. Find yourself a Stack Exchange site matching your expertise, and start providing such answers. Most of all, stop worrying about reputation. Reputation is a nice side effect, the core goal of these sites is to solve the questioners' problems.
