Using Back to My Mac to access files?

Can you copy files from one Mac to another when you are not on your network? When you are connecting over the internet?

Thanks.

If you use this, is there a reason to store files in a cloud service like Dropbox, Google Drive etc. if you can just log into your Mac from anywhere and acesss, update and copy those files? What am I missing here?

Thanks.

1. What happens if the Mac screen is asleep or the Mac is sleeping? Will Back to My Work?

2. Is there a way to use Back to My Mac from iPhone or iPad?

Thanks for your help.