Q: Upload all my photos to iCloud through Photos app.

I always kept my photos in folders instead of the iPhoto library (except for a few hundreds), if I want to upload them all to iCloud, do I have to import them all to (new) Photos app? Will the files be duplicated?

I won't sync those photos between all my Apple devices. I just wanna have a backup of them. I even bought more iCloud space already.

Or is there another way to make an iCloud backup of just photos from my Macbook?

Should I delete iPhoto app?