Comey had dismissed Hillary of any wrongdoing prior to that which was also highly unusual. You can’t ignore the stuff he did in support of her, which was a majority of his actions, and focus on the one time he actually did his job and act outraged.
There are millions of people who would lose their jobs if they tried to use their own email server to hide their work related emails. Those people mostly have much less serious positions than Sec State. There was only one reason to go that route. Hiding the emails even if and when she was caught was a better alternative than those emails being exposed. It is blatantly obvious to most people which is why it was important. It is also why her “wipe the server, with like a cloth?” responses were the real damaging moments of her campaign.
Why would the Russians prefer Trump to Hillary? Hillary and the previous administration were good to the Russians for the most part. The motivation to damage Hillary was one of hurting the eventual President. Hoping to cause a little bit of unrest. The story only persists now as a way to pass the buck on losing and an ongoing effort to delegitimize the winner. Which is a dream come true for the Russians by the way. So again who is serving Russia’s interests?