Although a complete newbie, I have been working for days on creating slideshows. I saw your question and thought I would share something that may work for your question 2.
Go to WP admin, gallery, options, slideshow and change your criteria for transition speed by changing the number in "Duration time".
I am not sure how to help you with your question 1. I guess I would start by looking at your template for that section under your the nav bar. Where ever that image is maybe try embedding [slideshow id=x w=2 h=2] the w will tell it how wide and the h will tell it the height. However, no clue if this will work. :-)
BTW - your site looks great!