Is there a way to get a more rounded hairline? (Photo)

Adding volume either with synthetic filler or natural fat transfer to the temple and lateral cheek area would help to soften the look.

What you have is almost certainly a normal contour of your forehead. Many males, in particular, will have a slight central forehead depression. Usually it is not noticeable. Often in very athletic bodies, it will be more obvious, usually, as you say, in certain light. Almost certainly not...

A two stage process, the first involving expansion of the forehead, could give you what you want without raising the eyebrows. You would have to undergo a 3 to 6 week period of distortion of your forehead which precedes the second and final procedure. 

I have never found suture suspension to be long lasting.  I have suspended brows with sutures after an endoscopic brow lift as additional support but wouldn't rely on just the sutures.  The needles used are like the Reverdin needles used in the past and suspending the brow is...

As long as there was no significant loss of full thickness tissue above (or below) the brow, post-traumatic swelling can cause all sorts of facial distortion! If there is swelling, the upper lid or brow will be in a position that will give you asymmetry. The nerve can be traumatized (usually...

You are very astute.     Some feel that the Endotines which gradually resorb over a year will allow the brow to fall back to original position.  Others feel that it is permanent fixation long after the plates resorbThe answer is probably both events-  some it is long lasting...