In the first shot I would have used a CPL to reduce the glare from the water. Otherwise nice work!
Buy a bag of Sakrete, about $4 at the store and mix what you need. Or buy a bag of sand and put it into the can, pea gravel works well too!!
I do not see anything wrong with the first and third photos. The second photo has too much shadow on the subjects face to be clear and crisp. First and third are about the the boy and that is what you want. Ask yourself "Do I like them" if so then what is the proble, don't be too hard on yourself!
Nice shot, great color and nice washed out background.
I buy all my equipment from www.adorama.com They are the best photo supply house on the web. They have excellent tech support with high qulaity merchandise and competitive rates. They also have a used equipment site that I have used several times with very good results. I purchased the identical lense from Adorama for under $1000. Works like a charm. Give them a try!!
I think they are good but I don't see anything spectacular, like someone below said, it depends on the wall!!
The railcar is stunning, go smaller with the watermark!
Go with the color, The BW are too busy to really determine what the object is.