Ok where to start I love the composition of these shots and im still a newb so take this with a grain of salt...................
#1 To me it looks like the right side of the pic is alittle dark I would slow your shutter speed down a tad more.
#2 In this one it looks like the flash is off cam left and to low , it is hitting her right in the legs and the flash needs to be turned down a bit.
#5 This is kinda the same as #2 flash off cam to left and to powerful and this would be an even better pic if you took the tripods and backpack out of the pic...........