Third to second crunch is a common fault and is just down to the synchros being worn. It is nothing to worry about, apart from being a bit boring.
You can either rebuild the box, replace it or adjust your driving style accordingly. I double declutch all my 3rd-2nd downchanges and this alleviates the need for a working synchro.
I imagine that the reversing light is just an adjustment thing on the reverse light switch.
H