I sided with myself purely because I didn't want to kill the Brotherhood. Anyway to side with NCR or someone else and not kill them?

Yes of course, do all the brotherhood quests and side with elder ncnamarra (the elder that rules when you enter the bunker) and he will suggest after you become a member that the NCR and brotherhood should not only make peace but ally against the legion.

NCR is only "bloodthirsty" because colonel cassandra has a "everyone is against us" attitude (unlike the ambassador who wants to ally with everyone). You dont have to kill anyone for the NCR (you can disconnet House from controlling his armies and leaving him alive)

Okay, thanks. Still get power armour though, can I?

Yup.
There is also an opportunity to get BoS armor when doing Veronica's companion quest.

Colonel Moore is a proven warrior and has fought in four tours against the Brotherhood. Her responsibility is to ensure that the NCR will succeed when the war begins and she doesn't think "diplomacy." It's a huge job and she doesn't like it when you don't do what she wants and won't eliminate the Brotherhood - but she'll be at the dam fighting right alongside once you make the deal. It gives me my only Infamy with the NCR when I broker the deal but since my Idolized status is very high, it doesn't change my rep.

When supporting the NCR, there are a couple of places you can do your own thing even though it's not exactly what Colonel Moore wants. It's my own way of being independent while helping them with all of their resources to defeat the Legion.

If I could use Yes Man to throw Col.Moore off Hoover Dam, that'd be great. She reminds me too much of Hitler.

Godwin's Law.

Why? They're ridiculous!

Aye.
As I take history seriously, I have to point out that using Hitler in this context (and related: when discussing Enclave) is ignorant, cheap excuse to justify one's opinion. Thus Godwin's Law.
If you relate everyone who takes military matters seriously with Hitler, somethings wrong, man.

You can side the BoS with the NCR with McNemarra in charge. And Colonal Moore, well she's paid to scope out all threats and is a bit paranoid. But she's doing what she's meant to. Someone has to do the dirty and bad stuff in all organisations. Theres nothing wrong with her or her orders in some situations. She is right about some when you think about it. She is ruthless and her plans for the Great Khans are bad, but tactically sound. She does'nt have to be nice but she has to get the job done.
To do anything other than kill Mr House is very cruel and very wrong. It is better to kill someone than do what disconnecting him would do to him. Treat like you would any enemy and kill him outright.
You can do what you like with the NCR quest save who you want, every single person possible if you want, so long as you give her a result.
It's not like NCR reps hard to come by anyway.

I always send the GKs to make their own glory, ally the BoS with the NCR and get the Boomers help. I always kill House and would never do anything else, that is beyond cruel.

No, she really does remind me of Hitler. She is so blinded by her fascination in the NCR, it's deafening. She thinks of everyone that isn't in the NCR to be worthless, and their lives are disposable. What did Hitler do? He exterminated the Undesireables. Gas them first, ask questions later. What does Moore do? Asks you to exterminate the Undesireables. Shoot first, ask questions later. Crocker should never have been disciplined as he was if you go the Hsu way of dealing with the Kings, nor should she fuss about a BoS allegiance, since the NCR isn't in a position to be fighting them. If they can't fight House, they can't fight the BoS without Legion interference. You could say" well, she's a tough lady and is strict, but that's just what we need", but then again that's what the Legion is for. Moore would be more fitting a person in power in Arizona, not the Mojave.

What's funny is that you get NCR infamy for getting them Power Armored super soldiers of the warrior caste of a high-tech militaristic society.