Check our articles for some basic what is a sump info.
Yes you will need an overflow if your tanks not drilled or if your going to be taking yoru tank down you could take it to a glass shop and have them drill it assuming its not tempered glass.
What you will need will be the following.
plumbing (size the plumbing diamater based upon your overflow drain and your pumps return size)
Assorted fittings (your gonna have to map out the route your pvc
will take and get the right elbows and whatnot)
Return pump (I like mag pumps)
1 way flapper valve (this is to help prevent a backwash of water from your tank to your sump in the event of a power outage)
Assorted ball valves (place these before and after the above valve and also between your pump and the plumbing so you can replace those parts easily
True unions (these allow you to take stuff out of the plumbing loop by just unsrewing the connections)
Thats the jist of it.