Limits of file size that can be uploaded to iCloud with a 2TB storage plan.

Apple does not offer specific information about file size limits, so one can assume that if its saying it must be less than 100MB, that's what it should be.

For very large files, there are other services such as WeTransfer, though those generally have a cost for very large files.

Yes, you should receive an email stating new activity in your thread.

You can manage your emails from this forum in your Profile page by clicking your profile icon at the top right of every page of the forum when logged in, and then on Preference in the menu it opens. From there scroll down to the "Messages from Apple" section to manage what emails you receive from the forum.

You'll be able to upload the full video provided it is not in Photos. Syncing to iCloud Photos has the video limit of 100 MB each. Your iCloud Drive can handle any file so long as it is not larger than 50GB.

You're welcome. You too.

Only if your intention is to sync using Photos. Otherwise, you can upload the entire file directly into iCloud Drive. I have multiple video files uploaded with sizes that range from 1GB to 12GB