1. It's very secure. Also whenever a security hole is found, the fix is out very fast.
Normally such couldn't happen, but it's always a good advice to .htaccess your adminfolder, too
2. Depends on the hack. Most of them are very very easy to install without any php knowledge
3. When you got acces to vb.com's member area you can enter your username to a form, and after that you can download hacks.
No waiting time if you do everything correct