hi!
im not a DP but i use a k3 really a lot. of course you can load the camera in daylight, but try to load in the darkest place you found, like in your car, van or your room. i always load in light and after 3-4 seconds of film runing everything looks fine. the same for unload.
about the lenses i recomend to buy a ring adapter for k3 to mount pentacon six lenses. i buy one from olex, a guy in ukraine, and work fantastic and the pentacons six lenses are cheap and brings good image quality.
http://geocities.com/russiancamera/
this is olex page, ask him for a ring adapter for pentacon 6 four your k3 m42 screw mount
have fun with k3!! play with speed ramps, are really good in this clock work camera.
Gral. Treegan