We well understand your problem from the days when we started ourselves.
A good place to find some reliable advice is at:http://www.hurdy-gurdy.org.uk/hurdy%20gurdy%20tips.html
Hopefully Neil (Brook) will see this thread himself and further offer his own take on this.
So long as your cottoning is really consistent every time you replace it (absolutely important this, same amount each time and well snugged up tight on the string, NOT loose) you should only have to touch the tangents very occasionally once you have them set up properly.
As a musician you will know about the difference between 'Just' and 'Equal' temperament. Unless you are playing alongside other instruments tuned in equal temper you will probably find that your Gurdy sounds best in 'just' temper as appropriate to D/G tuning in your case.
As you know it is simple to adapt the table on Neil's webpage (as above) from G to D ......... basically all the numbers remain the same, you just shift them all along to start at open D rather than G. Must admit we don't get too precious about being that exact, we just use the figures as an ideal to aim at and to get a better sound.
We found it all a nightmare at the start and spent hours messing around and not playing (wrong, just play regardless if no-one is to hear but you). We were a bit frightened of everything too, and nervous of changing anything. Take it a step at a time and don't worry, it will all get easier in due course.
Very best Wishes
Robin (and Marjorie)