Hey zher4883. So, about your questions for the WD Red and the WD Green drives... Generally I would recommend the WD Red drive as it's main purpose is specifically to be used for NAS and RAID systems as they are designed for that type of usage and are extensively tested for a 24/7 environment. If you are worried about the consumption, both the WD Red and the WD Green drives have IntelliPower which is a fine-tuned balance of spin speed, transfer rate, and caching algorithms designed to deliver both significant power savings and solid performance, but the WD Green consumes a bit less power than the WD Red drives. So at the end of it all, I guess you could go with the WD Green drives and they'll do the job, although if you want to get the best out of your NAS system, I'd go for the WD Red drives.
Hope that helps.
Boogieman_WD