Several places available. This is the one suggested for cruise passangers.
Elockers are located at the Downtown Ferry Terminal - Pier 2 (next to the ferry boarding platforms) which are accessible 24/7 every day of the year.
The aft cabins on 4 and 7 are VB so the same price. Are you sure that you are not comparing a SB corner Neptune with a VB? Or do you mean that you have already bought an aft VB and now the price is higher for an aft VB on another deck??