Look for the src attribute inside that tag. It will contain a long URL starting with https://fbcdn.net or similar.
No. Facebook does send any notification when you view, click, or enlarge a profile picture. The only time a user might know is if you download and re-upload it elsewhere (e.g., tagging them). Your viewing activity is private. view facebook profile picture full size full
For stubborn layouts where right-clicking is disabled, browser developer tools can extract the direct image source link. Step-by-Step Instructions: Open the target Facebook profile on a desktop browser. Look for the src attribute inside that tag