CZ 457 questions

I want to start to get into longer range shooting and had a few questions after some research and going through the links in this subreddit. I have access to a 50-200 yard range, which also hosts NRA silhouette and KYL matches occasionally.

From what I’ve read, most people suggest the CZ 457 Varmint MTR if you’re only doing bench rest shooting, and the other types of CZ 457s if you want to do offhand shooting. I imagine most of my time would be spent doing bench rest with occasional offhand. I would like to participate in the silhouette matches as well. Would the Varmint MTR be the best choice to accomplish this, assuming I would be okay with sacrificing some performance in offhand shooting, or is there a better option?

I also want to allow room for improvements/upgrades where I don’t have to change a ton of parts, so the factory model comes with acceptable parts, where I would only be looking to swap out certain things, like chassis, Lilja barrel, and etc.

Separately, I see the post on optics on sale and wanted to know if the Athlon Ares ETR is a good buy for 200 yards, or it would be excessive? It seems as if people usually shoot around 15x.

Thank you.