A few (PossiblyNooby) questions about BungeeCord

I am new to BungeeCord and am very interested in using it. I have pretty much everything setup but I have a few questions about it. Here are a list of my questions. (I have looked at some post on some of these but would like to have more info on them).

1. Seems how servers are offline how do I prevent cracked players from joining?
2. When creating the main bungee server does the bungee, main bukkit server, or both need to have more ram?
3. How would I get bukkit permissions to work on...

A few (PossiblyNooby) questions about BungeeCord