You can't compose the distortion of a wide angle away. The best you can do is even out the distortion between the foreground and the background really. Also, I think PS has some filter to compansate for the barrel look that comes with the territory
As I mentioned earlyer though, wide angle for architecture is not the best choice :>
As for the sky, I agree with Kash. It look unatural and not not were good in my opinon.
to sum up:
#1 I like it, the light in the bottom left corner is a bit distracting, might wanna try your hand at cloing it away. Other then that, great composition, nice capture of the moment and the clouds look really nice.
I don't know if it would be an improvement, but it might be fun to see the same shot with a longer shuttertime, so you could see the thingy move
Also, there's something weird with the colors, did you tonemap it?
#2 The composition of this is... well to put it frankly.. kinda sloppy :> I looks to me like a very touristish point and shoot image. I might have tried to move a bit more to the left of the statue, so that the spire of the building was more to the right of the image, that way you'd have more balance, also I think you've included too much of the base of the statue, see that bottom left corner where you got some of the lowest part of the base, which makes for a distracting colorchange, that should (imo) be cropped away.
As I mentioned, I don't like the effect on the sky, I've never seen a sky like that
#3 This is a very good picture, and I really like it. it's well composed, and you've done exactly what I was talking about in #2, you've composed it such that the background element (the thingy with the flowers) is not centered, and thus brings balance to the picture. Very well done
#4 Lovely photo, the dog might be slightly too centered for my taste, but that is a matter of preferance, nothing else

Good strong lines, well exposed just very nice.
All in all I have to agree with Kash, you're rapidly improving, but please lay off the weird skies :>
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