Multiple WP installations on 1 domain?

I’m in a situation where I need to run a 2nd WP installation to add functionality to my site. I want to start curating relevant news and information to my readers. The problem is that curated posts are quite different from normal posts and thus require a different presentation. So it makes sense to use a different theme for those posts.

Let’s say that my main blog is at domain.com. The news section would then either be at news.domain.com or domain.com/news. I wanted to ask the WP experts here what’s the best way to implement this?

If I run the additional installation at domain.com/news/, will the 2 WP installations interfere with each other? Will the .htaccess file of the main site override the .htaccess file of the 2nd installation? Since the 2nd installation is in a sub-directory if the main domain?

How would you guys implement this? Custom post types on the main domain? Multisite installation? On a sub-domain? Any other ideas?