Welcome to the forum!
Glad you joined us!
1/ tips or suggestions on how and where to buy the eggs of birds that have been bred for their feathes
Can't help you. It will have to be somewhere in the UK or possibly EU. The regulations and logistics makes it impractical to get eggs from this side of the pond. The recent fad of putting those feathers in your hair has run the cost of those feathers through the roof. You might try talking your local fly store and see who their supplier is and work your way back from that.
2/ any tips on incubating eggs
I plan to make an incubator
You might look through this section in the Learning Center of this forum.
https://www.backyardchickens.com/chicken-coop-incubator.html
any recommendation for a thermostat and is it best to position this among any eggs
The position depends on whether it is a forced air incubator or a still air. In theory and if you build it right, the temperature is the same in a forced air, so position should not be real critical. But if you look through the thread above, you'll see it does make a difference for some people. In a still air, since hot air rises, the position of the thermometer is important. You need to control the temperature at the top level of the eggs.
how critcal is humidity in incubation?
Very, but there is no easy answer for what to use. The egg shells are porous. They need to lose a certain amount of moisture as the process goes along. If they lose too little moisture, the aic sac is not big enough for the chick to switch over from living in a liquid world to breathing air. If the egg loses too much moisture, the chick can stick to the membrane inside the egg and won't be able to hatch. There are other effects too for both situations. The problem comes in that different humidities seem to work better for different ones of us. What works for me may not work that well for you. You would think that the conditions inside the incubator would be pretty constant for all of us, but it just doesn't work that way. I don't know what all the variables are, but one easy one is air pressure due to elevation differences. The higher you are, the lower your air pressure, so you probably need a slightly higher humidity for the same results. My suggestion is to decide on something, try it and try to be pretty consistent throughout the first hatch, and adjust based on results.
Some general thoughts on incubators.
Do not use valuable eggs for the first attempt, especially in a homemade incubator. Work out the problems with cheaper eggs.
You need some air flow to bring fresh oxygen to the eggs, more being required as they develop. You don't need a huge amount, but the chicks inside those porous eggs are breathing and exchanging carbon dioxide for oxygen.
They need to be positioned where you do not get a lot of temperature variation. Incubators generally don't respond very fast to temperature swings. So keep them away from doors that open to the outside, don't put them where the sun can hit them from a window, and don't put them where a ventilation duct can blow on them.
The important thing is average incubating temperature and humidity. Once you get the eggs to the proper temperature, a bit of a temperature spike or drop is not a huge disaster. You want to avoid that of course, but the center of those eggs take a while to cool off or heat up to where the chick dies. So don't panic at a slight hick-up. Same for humidity. It will drop if you open the incubator to add water or turn the eggs, but as long as it recovers fairly soon, that is not a big problem.
Stabilize your incubator before you put eggs in there, both heat and humidity. Experiment with it to see how you are going to raise the humidity for the final three days of lockdown before you put eggs in there. Lockdown is the final three days of incubation, where you stop turning the eggs and increase the humidity.
You need to consider how you will turn the eggs. The eggs need to be turned throughout the first 18 days of incubation for proper development of the chick.
You control humidity by the water surface exposed. Depth of water in a water reservoir does not affect the humidity, just how often you need to add water. So to lower the humidity, cover some of the water surface, say with foil. To increase humidity increase water surface, maybe by adding another reservoir or putting a sponge, cloth, or paper towel to wick water out of the reservoir and increase the evaporation surface area.
You need to calibrate your thermometer and hygrometer. These instruments can be off quite a bit due to factory tolerances. You need to know how far they are off so your can adjust the readings to accurate information. To me, the hygrometer does not need to be exact. It is good to know what the humidity actually is, but I use mine more to determine when I need to fill the water reservoirs than to worry about exact humidity. The thermometer is different. You need a thermometer accurate to within 0.1 degrees. Most of those used to measure outside temperature are accurate to only 1.0 degree, and you still need to calibrate them.
Sorry about the book, but you did say TOTAL newcomer. I suggest you look through the Learning Center at the top of this page and spend some time reading. Some of those topics are fascinating. And it is not as complicated or as overwhelming as it may appear from my post. What you are talking about can certainly be done.
Good luck, and once again,
