some hardware questions for building a new rig

[des56]

Have been reading several threads, and my understanding is that the GTX 1080Ti is the card to buy. And the Founders Edition has better performance, see GTX 1080 FE vs GTX 1080 Ti FE topic.
Thinking about buying 2. Will mainly use them for cracking NTLM/netNTLM/WPA2.

• Any particular GTX 1080Ti brand that is recommended or brands that I should avoid ?
  
• OS will be Linux,  should I go for Ubuntu 14.04 or 16.04 LTS or another distro?
  
• How important is storage? Is an SSD a must have?
  
• Is 32 GB RAM enough? Or can I expect higher speeds with more?
  

Thanks