configuration depends on how many RPs do you need during quarter. You can keep only monthly RPs or add a few weekly RPs.
By the way there is a Restore point simulator
for storage planning.
Is every weekly/monthly/quarterly/yearly a full VBK?
Is it possible to enable deduplication in Server 2012 to save on the VBK files or is this not going to help?
Yes, it is possible. Please review this exiting topic for details: Best Practice for MS Server 2012 DeDup Repo