The firmware for the K3 is here http://www.ricoh-imaging.co.jp/english/support/digital/k3_s.html
The choice of lenses is more of a personal preference for what you are shooting. Personally I am more mid range than macro like your 18 to 50. If you have a converter ready you can use it in a pinch instead of hauling all the lenses around. Provided you don't mind loosing depth of field.
Any luck with that firmware page? There is a great discussion on TC here: http://www.dpreview.com/forums/post/53585548
THat is good site, I am more of a Canon fan though :)
Better to become a South paw! I like Nikon but they are not cheap.. Canon eos6 is a good feather weight but if you add 1KG in lens then you have no gained any benefit http://www.trustedreviews.com/news/canon-eos-6d-announced-a-lightweight-full-frame-dslr-with-gps-and-wi-fi