First we try and answer all questions here.
I have built a large wooden box 3X4X8 with 3, ft walls. The top has a hinged door and part of the door has been cut out and chicken wire put over the hole so I can see in easily. The inside has been lined with a tarp , stapled to the wall to allow for better disinfecting. All new birds stay in there for minimum 30 days.
The main thing, IMHO, whatever you do, it has to been totally contained so no other critter can act as a carrier and spread virus and or bactieria from your quarantine area to your established flock.
Personal items: I keep a bottle of rubbing alcohol and paper towels by the quarantine box. If I touch the animal or inside the box, (water, feeder, etc), the last thing I do before leaving the area is wipe my hands and arms down with alcohol.
If your area allows the birds access to the ground I would invest in the plastic booties and USE Them.
Hatch your own replacement for culls, yes. Main way of improving the flock, I cull for egg size and looks, (most of my birds are duel purpose breeds).
The only time I would bring an outside bird into an established flock is if the bird had outstanding features that I need for flock improvement, otherwise a strict culling program should handle all other problems.
Also dont forget , if you are really trying to establish bio-security, you need to be aware that people can carry viruses from their flock to yours.
That is why you will often see breeders , who have worked for years to improve their flocks, not allow visitors on their property.
How to start to develop a good heritage flock. Start with good building blocks, GO TO LOCAL APA Shows and meet and create relationships with breeders breeding the birds you are interested in. If you do not have much money , begin with purchasing their culls. In the beginning you can mix lines, that fine , you are establishing a line of your own. Many breeders will not sell chicks or hatching eggs, why, because the main way to build a flock of winners is to hatch all you can and cull like crazy. I have a friend that will hatch aprox 600 chicks each year, out of these 24 might end up in his established flock. He never sells chicks, or hatching eggs.
Well that gives you some ideas to start with, remember these are my opinions and you know what they are like, we all have them