Hi guys, job's done!
I went to the hardware store to get the nipple. Then I decided I would have a go at trying to fix the thread with a steel fitting that I could screw onto the pipe in trying to fix the thread (since the pipe material seemed a lot softer than the steel fitting). Doing that a couple of times worked really nicely and for $1.39 I had my own little pipe-threader. Pipe fixed.
After that it was a walk in the park. Got everything back on the car in less than half an hour and ready to roll. Of course I first needed to charge the battery because I left the trunk open and -- since I thought (again) I could handle this one with the battery connected -- the result was a no go on the initial start-trial. The clicking starter relay is starting to become a rather familiar sound since I seem to pull this on myself pretty much everytime I work on the car. Anyway, put the charger to work and an hour later car was running beautifully!
Now here's the thing that surprised me. I thought the water pump wasn't gonna make a difference for the running part of the engine (at least not noticable) but it seems to do so anyway.
In idle it revs slightly lower (I think it is around 600-700 revs, maybe 800) than before (+/- 800-900 revs) and I need to crank less before she starts (which truly amazes me!). I know, doesn't make much sense to me either, but it really seems that way. Any clues?
Temp wise things are much better. Before (we've only had this little truck for three months now) the dial was always around 200-210 and I kind of thought that was the way it ought to be (although of course I should have checked that in the manual, but didn't) and now it's closer to 190-195 where it's supposed to be. Actually, I was so used to the dial sticking close to the vertical (200-210), I thought the engine was too cool. I supposed this improved cooling is either the thermostat (which I also replaced) or the pump, or both. Best of all, no more leaking!
Thanks again for all the help and input. You saved me from many mistakes and I've learned a lot, ranging anywhere from plumbing to inches and bolt sizes. Great!
If you guys have any clue why my car runs different (better?) than before, and how that is possible with just replacing the water pump, please let me know! I am clueless (but happy!).