Lightroom v Lightroom Classic & Storage issues

I need some help with Adobe & Lightroom

I recently made the switch to using Lightroom CC from Lightroom Classic and i'm storing all new photos in the cloud where i have 100gb storage with Adobe

On the Adobe cloud I already have 30gb worth of photos stored but Lightroom seems to be storing double that (60gb) on my laptop in library files, how is that even possible?

I wanted to increase the cloud storage up to 1TB but I was quoted a ridiculous price. 

I currently pay £373 annually for the full Creative Suite with 100GB and to increase it to 1TB I’d need to pay £655 - Basically charging me £282 for 1TB storage when i could buy an external 1TB HD for £30

I'm considering moving back to Lightroom classic for the following reasons…

1. I won’t have double the storage amount of my photos on the laptop unnecessary 
2. I’d be able to run/store everything on a 1TB HD without having to pay £282 for additional cloud storage

Some questions.

Q - Does anyone think that moving back to Lightroom Classic would be a mistake?

Q - Is it easy to migrate photos from Lightroom CC into Classic keep the folder & album structures i set up

Q - Would i be able to initially upload a new photos to Lightroom CC so i could edit them on the go and then transfer them over to Lightroom Classic for storage and any future changes

The only negative thing i can see from it would be not being able to edit on my tablet and have it automatically synced with the laptop