To be sure, there are a lot of times when you can't contain the entire dynamic range with your camera and you will have to blow things out. The one place where a lot of people will notice the blown out spots is in prints. The transition between white (with detail) and a blown spot on a print is much more noticeable than it is on a backlit screen. This might not matter so much on bright backlit afternoon shot, but it will be noticeable on a shot like this. I say print it and see what you think, it might work out just fine. Also the red channel on your camera is much more likely to blow first (really noticeable in skin tones like #4). One thing I do is to really watch the red channel histogram when shooting portraits.
In #1 I'm talking about the composition weight. I like how you've framed her in the doorway (assuming this is a doorway). The shot is primarily a high key shot, but there is a lot of dark background showing in the top half of the frame. This makes the photograph seem a bit top heavy to me - within that open area, the top half is much darker than the lower half.
I know shooting at workshops is far from ideal. You will almost always not have the ideal position, angle, etc. and it's more about practicing and sharing ideas than getting a perfect shot.