Hello

I'll be starting my first hive...maybe hives...next year and I have a bit of a concern. All medium hives seem really popular on the internet so I figured that I might go along with that. However, I have two concerns with the philosophy vs deep/shallows.
A)
Shouldn't a brood nest within a deep hive body be bigger than in a medium? Meaning with more brood the hive should be stronger in deep/shallow configuration. From what I understand the hive picks one section to raise brood so I figure I'd want them to take the biggest section.
b)
Also since the bodies are all medium...could I have trouble as a beginner with honey supers vs brood supers? The queen could essentially be laying brood anywhere, or moving the brood nest around since there wouldn't be a preference with all the bodies being medium. People don't seem very concerned with it but since I don't have any experience I feel like it could be a mess.

Again, no experience as a beekeeper so my assumptions could seem silly, but they have been bothering me. Since I want to keep bees but I cant yet I've been obsessing about it.