Hi Questions and welcome to Seven Forums.
To answer your questions.
1. Yes proveided there is sufficient free space on the 1.5 TB HDD. An image will normally take between 50-60% of the size of the data you are backing up. That is the used data not the size of the disk. The restore will return your disk to the state it was when you took the image.
2. It is not truly a clone as it doesn't normally back up unused storage but in effect it is a clone of all the data that is on your drive.
3. You don't need to worry about that. The image is just a file or files that contain enough information to put everything back the way it was when you do a restore.