@3scoutsmom did a good job of covering it most but I’ll add my insight, as an upperclassmen NMF.
1). You have to apply but you don’t need to write the essays. Literally just write “National Merit” in those boxes and you are accepted.
2). 1/4 is not an accurate number. I’d say maybe 10% of classes are related to honors for me. You have to take roughly 3 classes of honors that are typically just better versions of gen-eds. I took honors calculus, but there’s bio, english, etc. These are just generally a more intimate, slightly more challenging version of the general sections. Then you have your perspective and colloquium courses, these are each one course and are a humanities course taught within the Honors College. They have almost 10 options for both of them every semester and they vary widely. I really enjoyed them. Then you have your honors research requirement, which isn’t really a class. It’s just working on a research project with a professor. Let me know if you have more questions about this, because it can seem daunting at first, but let me assure you it isn’t a big deal to complete these.
3 & 4 are covered very well by 3scoutmom. I lived on the National Merit floor of Walker my freshman year and enjoyed it tremendously.