Guineas are horrible to raise. They are super-loud and go off like a car alarm. They are banned in a lot of areas because of it. My neighbor had some. After about 3 days I had to go over there and have a talk with him. If you like your neighbors avoid getting them. Ducks may be much better choice.
I'm off-grid and have a pretty solid homestead set-up. I always run chickens ..just for eggs as none of them end up on my tables. I have made the choice not to butcher my animals and mostly eat fish (fresh caught by myself) When my hens get older and stop laying they live their lives out with the rest of my flock. I treat my chickens like family but that's just my thing.
If you are making your money by selling young chickens look into getting good Roosters and incubating the eggs. But I dunno' I think you can buy baby chicks for under 5 bucks online and have them delivered to you in a box. It may be cheaper than going through the incubating process (from a cost and time thing)
I make my dough selling the eggs as I contracted with a few big restaurants up here. Weekly deliveries and a pretty good return on my investment.
2 Big things: Know how to keep parasites off them (Diatamaceous Earth is what I use, in their feed and externally and sprinkled in their coop) and read and learn about egg-bound Hens (life threatening) because sooner or later you'll encounter it.
All my chicks get socialized with me from day one. They are tame AF. I am a huge fan of Buff Orphingtons for many reasons...esp. as they are a cold weather bird and mellow (good layers too). They all love to be picked up, walked around and they'll sit on my lap. Pretty fun creatures to hang out with and observe what they do all day. I'm retired so I can do that.
I like the idea of the loud shitheads running around. I don't have a dog and I'd like to have an alarm system.
My neighbors don't complain.. We're all kinda planning for dry times. They say when they hear my 100 roosters going off they hear security. I have really good neighbors though, we share food and wine. I believe there is a feeling in the air now that we might soon need each other.
We eat ours. Once we looked down the awful rabbit hole of commercial chicken production we decided we'd rather eat these.. My chickens are still babies at 5 weeks, there's are fully grown and as big as a turkey in 5 weeks. It must be more than just a cross bred chicken to cause that. We like the chickens but they live out their purpose when fried.
It's much easier to raise them when they're tame and easy to handle.. Its definitely worth the time to make friends with them.
Up to this point I had been ordering chickens.. With great luck. Out of hundreds of chickens ordered I probably lost 20 in the mail. But... I ordered 100 pullets a few days ago and 40 of them were dead on arrival. That hurts.. The hatchery says they'll call me to make it right next week, and I sure hope they do.
This was going to be my last order anyway, as I've grown out some breeders from the hatchery stock I'd been getting. I bought 4 Hovabator incubators, so now I can set about 160 eggs.. with some luck I should be able to hatch 100 chicks a month. I can improve the quality and size this way. Only problem is, like you say, grown chickens do have more problems than growing chickens.. as far as egg issues and parasites.
The first batch of chickens I got were from the local auction and they all died a nasty chicken flu death.. That was disappointing and I almost quit right there. The key is to never bring chickens home from random places. Once you do, you'll have problems. I do use our auction for selling, with great results.. since most of the chickens there are sick or otherwise fucked up, mine shine.
It's great that I have a chicken friend now, I know my wife wants me to shut up about them. Haha I tried the chicken forum.. That lasted about 10 days, I basically got thrown off for saying that chicken wire was an acceptable building material, among other things. Haha