To be local moderator there are only board specific requirements.
For example, if you apply to be local moderator for the scripting board you should possess enough knowledge to fulfil that position properly.
Experience is hardly required but a bonus.
Most people start their careers as local moderator.
To become Smod you need to be experienced, known and trusted. A lot of responsibilies come with that job and they need to know that you have the common sense etc to handle it.
There are no certain requirements either besides having enough experience.
You can apply for all positions any time, you will be discussed and accepted if they currently are looking for new staff members and consider you trustworthy and valuable.
Every once in a while they make recruiting threads such as this one.
http://forum.toribash.com/showthread...wpost&t=286921