I have been hunting/shooting the 7mmRM cartridge for over 16 years now. I've had about 5 of them during that span, it's one of my all-time favorites. Berger 168 to 195 grain bullets are good options. If you plan to shoot heavier than a 168, I'd go for the 1:8 twist barrel. Precision accuracy can be achieved with any cartridge, the quality of the rifle, ammo components, and load skill is what determines the accuracy.
As for elk performance, I have no idea. Never shot an elk, but I know that lots of people have killed elk with no issues with them. One guy on here killed a huge moose at almost 1,000 yards with a 7mmRM.