Hi and welcome Tom
You are one lucky sod, I mean that in all earnesty! If its in good working order you have a great outfit there. The Fisheye is very rare and worth more than the rest of the kit put together. Last I saw one on ebay they were asking $2000 for one!
When it comes to using the Kowa. Its not difficult once you know how.
Loading film. I tend to do this with the back off. To release the back the camera and lens need to be cocked. Don't use the crank, use the wheel only or you might chew up the gears. At first you'll notice the wheel has a bit of resistance, that's the mirror and auto blackslide being moved down and back respectively. The next half of the cycle feels lighter. Once cocked the film back can be removed and so can the lenses. When loading the film with the back removed you can wind on with a wheel on the back. Once remounted fire the shutter and wind to frame one. The first frame takes a bit of winding, that's normal.
Film loading is not difficult, just make sure the pressure plate and film counter are set to whatever film type you are using, 120 or 220.
Removing and attaching lenses can only be done when cocked. Rotate the breech lock anti clockwise til it stops. Then press a small chrome button lower left corner on the front, opposite the shutter release. Then rotate breech lock anti clockwise until red markers line up. Lens is now loose. When off camera, test lens by pressing a small button on the rear face, shutter should now close. Set speed and rotate sliders on the rear clockwise and aperture blades should stop down to desired setting and shutter should fire. Cock lens by rotating sliders anti clockwise until red dots line up ans there's an audible click. Remember lenses can only be remounted when cocked.
The lenses are auto stop down, meaning you view everything at max aperture. If you want depth of field preview there's a small lever on the lens for that. Check lens aperture blades for oil when you are at it. There shouldn't be any. On the other side of the barrel there's a switch for shutter mode. The middle and upper settings are for flash sync mode. One for electronic, one for old style flashes. The lower setting is for self timer. If you use self timer the mirror will lock up straight away, which is why I use it for those shots I want to be as sharp as can be.
I have an 85mm and a 150mm lens for my Kowa. And they are very good. Better than I expected. More than sharp enough in my opinion, the 150 in particular I like for its almost 3D like rendering.
Test the lenses, and try the kit out. And if you are not particular you can sell if for a nice premium. If in good condition camera and normal lens, the 85mm, fetch anything between $200 and $450 on the ebay. The 55mm $200, the 150mm the same or a bit less. Haven't seen the 40 and 30mm on ebay ever, nor the 250mm. Tubes fetch $50-75 typically, grips $30-75, film backs $50-100, polaroid backs more. And the 19mm fisheye, well as mentioned earlier, can finance a whole system on its own.
Feel free to ask questions, here on in a PM. I'll do my best to answer.
