Standard track will allow up to 5mm glass, maybe 6mm if you go to somewhere other than bunnings.
The type is up to you, 5mm will limit you to either standard glass (called 'Float glass' ) or safety glass ( also called toughened glass). Laminated is a choice but the thinnest you'll get that is 6.38mm
Depending on how tall the the unit is, I'd put safety glass in all the 'shelves' if you can't bolt it to the wall.then if it does topple forward and you react by lifting your hand theres less chance you'll put your hand through the glass and slash your wrist. If you can bolt it to the wall then safety glass below waist height and standard glass above waist height.
Don't forget when you're measuring the gap for glass to allow 11mm less than the vertical measurement of the gap, this allows you to install the track and get the glass in and out without it falling out. ( check the instructions with the track for the distance you subtract from your opening, different brands may differ) and the thicker track goes on the top