What is the best thing to do? Get rid of the elder or keep him, how do I get the brotherhood of steel to help me in the final battle and is it possible to get power armours in NV?

Thanks for now.

Keep the elder, only he will give the option to ally with NCR.

Yes, there are power armors in the game. Check the wiki for a complete list. You can get the training after becoming a paladin or at the end of Arcade's companion quest.

I like to do all of their quests. Keep the elder. Get power armor training. And then massacre them all with a chainsaw.

Edit: If you are going the NCR route then you can ally with the BOS. Here is the link for the wiki info: http://fallout.wikia.com/wiki/For_the_Republic,_Part_2 just scroll down to the Brotherhood Of Steel section.

how do you get the training? The elder goes through the speaking part then it goes 3rd person view and i can't move nor part the armor on. any ideas or help, thanks.

did it freeze? once you did the last mission for them and join, the elder trains you power armor and gives you one. if that didn't happen, there must be a glitch.

You ask to be a member of the brotherhood, then the elder gives you a quest. Then when you finish it, you are a paladin and the elder gives you some power armour and training

Thank you vey much for the help

NOTE: after finishing Still in the Dark, you need to leave the bunker entirely (i.e. exit all the way to the wastes) and then re-enter prior to speaking to McNamara and asking to join the Brotherhood, or he will not have the appropriate topic available. It may also be advisable to FT to another location and wait a day or two before re-entering the bunker, although I have never had to do so.

If after re-entering the bunker McNamara does not offer the proper topic, then exit the bunker again and do the FT-and-wait routine; give it 2-3 days to be on the safe side and then try again, and McNamara should now have the proper option available. I recommend making a fresh save after exiting the bunker (remember, you must exit to the Mojave Wasteland), so that you have a close point to reload to if the waiting trick does not fix things, since in that case reloading will be the only option (if that fails, try exiting the game completely prior to loading the save).