As far as optics go I was looking at the beast, or the Bushnell elite tactical 3-21.
Do not buy a Bushnell if you want a quality scope. The best thing about them is the warranty but compared to a nightforce they are junk. I had an Elite 6500 and had to get rid of it because the glass sucked compared to my NF and Sightron scopes. Once you shoot through higher end glass it's hard to go back.
If you want a quality scope but don't want to pay for a Nightforce then have a look at the Sightron 2.5-17x56 in either the SIII series or the new S-Tac line or the 1-7x24 if you want to keep the size and weight down. If you want to shoot really far and sacrifice being able to do much besides shoot off the bench then they also make the 6-24x50.
On an AR I would try to keep the optic a little smaller so the rifle maintains some versatility. It all depends on what type of shooting you plan to do with it though.
Sightron makes great scopes for around $1000. The glass quality is close to that of Nightforce and the turrets track very well.
Check out Mystic Precision for Sightron, Jerry is a great guy to deal with and I had mine in my hands within a week of payment.
As for your question about twist rate. If you want to shoot longer ranges (500+ yards) you want either a 7 or 8 twist. 9 is too loose to shoot the heavy stuff at distance.
You don't need a brake on a 223, especially a longer heavier barreled rifle unless you plan to 3-gun with it or do some type of shooting where quick accurate follow up shots are required. With the longer heavy barrel that probably has a rifle length gas system as well recoil will be smooth and gentle, your wife won't have any complaints shooting it.
A brake will always be louder for yourself and those around you but they aren't terrible unless you start getting down into barrels 12 inches or less.
Your options seem strange, Les Baer or Daniel Defense and then Nightforce or Bushnell? High end or middle of the road both times. If not for the cost the choice seems obvious to me.