The rig that you got on the link form best buy is only has one GPU which is the most utilized component for mining. I would be much better if you buy the components separately. If you are looking for some specs here it is for around the same price.
Intel Pentium G4400
Gigabyte H110-D3A
G.Skill Aegis 4gb 2133
120gb SSD
750w PSU(Brandss from Corsair, EVGA, Fractal Design, Rosewill or Seasonic are preferable)
4x Sapphire PULSE Radeon RX 580 8GB($300 at newegg right now)
Custom case for your mining rig.
The CPU, Motherboard, Ram, SSD and PSU should be around $300-$400 USD so the remaining $1200 could go for the 4x Sapphire PULSE Radeon RX 580 which is good for mining right now. For your case you can just build it your self their are many tutorials out there on how to build it.
Yes correct but you don't really need the SSD, you can reuse any old SATA drive you have running around. Makes no difference in mining.