Yes its totally free for everyone
Yes, you will be notified by email when you enable this function by clicking on the setting tab.
Yes, you can protect your files with a password.
If you reach the limit of whatever you have you are unable to send more files. For sen more files you need to delete old files from your panel.
You can send upto 5GB files for free and 25 GB storage.
Yes absolutely safe we used amazon storage for better security and safety.