iCloud Photo Library and my internal hard drive

I have a large collection of photos and videos in Photos. I think it’s about 800 GB. I recently turned on the iCloud Photo Library (and it took forever to get everything into the cloud). I chose to optimize Photos on all my devices. Thus, all of my photos and vids are now in the cloud. I have a backup on an external drive. My iMac recently died. I just ordered a new MacBook Pro w a 1 TB drive.

1. Is there any way to know how much internal hard drive space Photos will use on my new laptop when I turn on iCloud? I don’t want to download everything from the cloud onto my laptop’s hard drive. Will my laptop’s hard drive only ever contain those photos and videos I bring down from the cloud when editing?
2. Since I chose to optimize, is there a way to limit how much hard drive space Photos will have access to?
3. My typical workflow is to create new vids on my iPhone (volleyball) which will work their way into the cloud. I will then want to edit the vids on my new laptop by pulling some down from the cloud. Once I’m done editing, I will no longer need the vids on my laptop’s hard drive. Is there a way to keep my hard drive from getting cluttered with the vids I’m no longer editing? Somehow bring them down from the cloud, edit them and return them to the cloud, without leaving anything on my hard drive?
4. How do I remove photos and videos from my laptop’s hard drive without removing them from the cloud?