3 Original breeds to create all the following;

[Tom_DarwinNT]

If you are still considering Australorps, their eggs aren't necessarily cream. I have gotten a few that were quite a light shade of tan but most are medium brown. These are the last seven eggs my Australorps have laid.

Ok that’s helpful, thank you. As I only have google and here to compile my info, any and all advice is appreciated.

 

[NatJ]

I assume the Barred rock x Silver laced Wyandotte would be a decent dual purpose bird?

It should be.

 

[BGMatt]

If i wanted to breed birds that would allow me to have the following outcomes;
White Eggs
Brown Eggs
Blue Eggs
Green/Olive Eggs
Sex Link (Red or Black)
Dual Purpose for all if possible.

How many original breeds of chicken would i need to start with? I understand i would need to start with the Araucana for the blue eggs and for crossing with a white and a brown for different colors but i am unsure which breeds would be best to achieve all my goals with as little as 3 maybe 4 original breeds.
I would line breed for the pure bred heritage birds, cross breed for the sex links and easter/Olive eggers.

What breeds and genetics would work best and would it be possible to start with just 3 different breeds?

I live in Northern Australia in the tropics, so birds that are able to handle warmer temps and handy foragers would also be an advantage for the newly fenced areas.

So I took a bit different approach to attacking your scenario. You say the reason for wanting to create a sex-link is so you can sell people good laying birds and be able to tell which are female at a day old, but egg color for that doesn't matter. Well why not look at an Auto-sexing breed or two? Cream Legbars would be your blue egg layer and if bred together are 100% sexable at day old. Rhodebars give you brown eggs and are sexable at day old. Crossing those two breeds would give you green egg layers (these I think would also be possible to sex at a day old as any barred variety is but I'm not 100% sure due to different base patterns). Both of those birds are ok at being dual purpose although a bit on the smaller side. So maybe a white egg layer like a Dorking that is bigger bodied and a bit more meat. That meets all your requirements except a sex-link, but as stated if purpose is to be able to tell 100% pullet from cockerel at hatch, the breeds I suggested would give you two breed in two different egg colors you could do that with.