Unfortunately, you will not be able to accomplish having 3 text boxes in the same line and having the labels show up above the text boxes. The labels will be displayed together to the left of the elements.
Also, you will not be able to display 2 different fieldsets side by side. Form builder is only set up to build the forms vertically.
I apologize for the current limitations on the product. If you want to see these features implemented in a future release, please post in the wishlist forum.