trackpad doesn't depress

• No.
• I can click mine almost to the edge near the space bar.
• I've never looked at whether the left was lower than the right, or if the right was lower than the left.
• Does the trackpad work?

 

I can't click any closer than about 3/4" from the top.

 

I had a very similar problem with my trackpad for a long time, until I loosened the screw on the bottom of the pad itself.

The ifixit guide mentions this screw here: http://www.ifixit.com/Guide/Installing+MacBook+Air+13-Inch+Mid+2013+Trackpad/15235/2

You shouldn't have to replace anything, since the screw mentioned in Step 10 of that guide is the likely culprit. I am not sure if it void your warranty to get to the screw, so you may want to take your computer to an Apple-certified repair professional to make the adjustment.

Edit: It is typical of Apple laptops to not 'click' in the top 1/4 of the trackpad, but it should still accept capacitive input. The tightness of the screw in step 10 can adjust the 'clickable' region.

 

I have a 2013 13" MBA and the trackpad does not click anywhere closer than about 3/4" to the spacebar - pretty even left to right. Scrolling works over 100% of the pad, but clicking only in the bottom 75%. I had never noticed it until I saw your post, so it clearly doesn't impact the way I used it.

 

The trackpad is fixed from the top, so it's going to be easier to click it the further down on it you press.

Also the right side of mine is just very slightly lower than the left side, and is only noticable when comparing the grooves. It doesn't bother me at all and I don't think it will every become more of an issue.