1) looks a tad over exposed. Were you pickign up the meter readings from the grass or the sky?
2) Preety good, colour is right but I think the positioning is a tad out, i take it the pics 1 and 2 are from the same spot? You need to stick to the rule of 3rds but that one dosnt seem to be picking up the the extremes of the landscape. It looks a bit flat... Perhaps getting lower to the ground?
3) Looks great in b+w and the "model" adds to the composition, again maybe lower to the ground may give more depth. Also appature settings may have needed to be changed slightly.
Keep up the practice, its hard work figuring out all the settings and getting the composition right, but all worth it in the end when you get that amazing picture