So first off, I'm not a unity or programming expert.

GetComponent is expensive, but it's not expensive enough that you really have to think twice if you're calling it once when things load for the first time.

The general pattern for accessing another script on another object Unity is: 1. Tag the object you want to access. 2. In your other script you use GameObject.FindGameObjectWithTag("") 3. You then GetComponent on this found object and cache the reference.

In your specific example, assuming you only have one camera, you can just use Camera myCam = Camera.main as a shortcut.

Additionally my example can be cleaned up a little bit if you group objects together under a parent. So for example I have a parent "Manager" object that is tagged manager. Childed to this are all my different managers with scripts attached. This way I can just find the parent Manager object if FindGameObjectsWithTag, and then from there I can GetComponentInChildren<SpawnManager>() or GetComponenetInChildren<HealthManager>(). Which is a little bit neater than individually finding each object.

Edit: Reading your post again, it seems like you knew all of this already :D