2012 with hyper-v is super stable since. Once you have the host setup with the basics (updates, IP reserved/static, Hyper-v role installed) you never really should be touching it. At that point every other role should be in a VM. Now since you have technet use 2012. Since you'e new at this waiting for R2 really doesn't matter you probably wont need most of the new features yet. Even if you had to bare metal install R2 and export/import the VMs, its pretty simple.
For customer data backup I'm only counting 2 locations I should see 3...PC repair 101. Second I would keep client data separate from personal/Lab data. For archive storage of client data a cheap used NAS can be had for under $100.
As for the hardware. Not enough information. AMD 6core is fine as VMs are not particularly taxing. 8GB of RAM is really not enough about the bare minimum actually. Consider moving up to 16GB now while RAM is relatively cheap (its going up fast). You do not list any disk specs other than an SSD for the os. What size is the SSD? What other disks do you have/plan to have? SSD for the host is a waste use it for VM's. Even a single VM would see more benefit. If its too small use it for drive buffer cache.
It would be a really good idea to listen to the podcasts Jim recommended. Once you come up with a plan and present it here, we can help you review it and you can make an informed decision.
Self-edited thoroughly because I'm ozone and bad for the environment....