Wow! I haven't visited the forum for just one day and look at the catching up I had to do!
1) About the male-female issue, it does seem that the technical field of origami (おりがみ せっきい, Origami Sekkei) is dominated by males. I have met only one woman who was good at technical folding, and not very good at modular and geometric stuff. I don't know exactly why, but it's probably for the same reason that there most of the students in the mathematical oriented fields are male.
A curious point raised by bshuval several weeks ago, when we watched a video about Lilian Openhimer on our monthly origami meeting - it seems that origami was brought and populorzed in the west by females, but since then the male have "taken over" the field. I think it is much more apparent in Japan, where origami is an art traditionally taught to female children by their mothers, and yet today the majority of designers and folders are male.
2)
My first model folded, many moons ago, was The Swan, but I wasn't completely happy with the finished model and made a few minor adjustments, (nothing extravagant, just pleated the wings so they sat well and crimped the neck to create a more elegant form)...but I guess many folders (far, far more acomplished than I) make such changes..and maybe if they make enough changes they come up with a 'new' model.
I think this is a very important point. Most of the modern origami models have their own base. Basically, a base is an origami models with enough flaps to create the intended model. I trully believe that a folder should use artistic license once the base is folded, and feel free to steer away from the written diagrams. Most origami diagrams go through three stages:
a. Finding the refference point/s. (Lots of folding and unfolding).
b. Folding the base.
c. Finishing the model.
Although stages a & b are usually require very accurate folds, at stage c folding "inaccurately" is not dissastorous, and can even achieve better results.
It should be noted that this does not mean that once you finish a model it becomes your own design. A lot of the designing went into the base.
3) The dreaded close sink.
A closed sink is like an open sink, but the layers are rearranged. Try open sinking the waterbomb base, look inside. All sides will be arranged the same. In a closed sink, the inner triangle will not be trapped inbetween the two flaps, it will be on either side of them. Step by step its, fold a water bomb base. Fold closed point to the bottom. Unfold. Fold paper in half. Fold the two diagonal creases (the two points at the closed top) to the middle line, bottom. Fold the top point down. Bring one layer to the front (flip over the first layer from the back). Hopefully you now have a closed sunk waterbomb base.
An excellent explanation!!! I rarely see anyone using this approach in explaining how to fold a closed sink. In case it helps, I have several pictures of folding a closed sink on my webpage (under articles). At the bottom part I also have pictures of the "alternative" and very simple and clean method which is sometimes possible to use, based on the concept presented by Joe W.