Christie Photo
No longer a newbie, moving up!
There is something in most film SLRs / medium format called a "focusing screen." They're designed to make it easier to tell if something is in focus. You might see a circle in the middle of the screen, and the two halves only line up if it's in focus, or something like this.
Yup. It's called split-image focusing.
Medium format finders are not as bright as 35mm and can be a challenge at times. Beattie Intenscreen was popular, though I never used one. Also, I never used a prism finder... mostly because of the cost. Working with a waist level finder had me standing on a stool from much of my work.
I shot the vast majority of my portraits with an RB67 and a 180mm lens at f/8.
Good luck!
-Pete