There is always a risk. We have a process they need to go through before they get access. Even once they are staff I have checks in place to make sure that if they do something malicious it can be easily reversed with backups. It's pretty much a waste of time for them. We do ip cross referencing now so no proxy players will not be accepted and instantly banned. Generally they have access to ONE server not the whole network. I mean if someone wants to play the "long game" just to do some griefing then we can't stop it but we can fix it with the click of a button. We have already added lots of people through word of mouth references from current players. We just need people with more skills.
Just to add I found two of my best Devs on here so I hope that my luck continues!
As far as adding servers goes. If a server does join the network they will only have access to their own server and all bungee config is done by me pretty much.