What I am going to write is the good and the bad that I have found about guineas. So it maybe different for others but I am glad you are doing your homework before getting them. I don't want to talk you out of getting them, I want you to get them and enjoy them but there is more to know than the internet telling you that they can free range with little help from their owners. Oh and please excuse my spelling errors and I wanted this to be kinda funny so other guinea owners can say, "I have been here!!!".
Ok, colors ..... One color isn't better than another in guineas. I think it's all in what colors you like. Some say the white ones or the lighter color ones are more prone to preditors but I haven't seen it. I live on 900 acres and my biggest preditor is the road out front of the farm. They love to stay in the road or cross the road to get to the corn field. Mine free range during the day and come back to the coop at night to roost. I trained them to come back by ringing a cow bell when I fed them treats while they were keets and it worked. They will come from any where in a hurry if they hear that cow bell. I would be in trouble if a cow with a cow bell on went down the road because I think mine would follow it. LOL!
As for how many to get ..... that's up to you but guineas like company. They seem to do better in a flock but there are some who only have one or two that do just fine. With me .... guineas are like potato chips ..... you just can't have a few. You get addictive esp during hatching season. "Hi, my name is Bonnie and I am a hatch aholic and I can't stop!" Beleive me, it is so fun to collect eggs, use incubators, watching them hatch to see what colors you got, taking care of those little keets, watching them grow up, keeping them in the coop/run for 5 to 6 weeks before letting them out for the first time so they know where they live, wondering if they are gonna come back the first time you let them out, etc..... But there are also bad times too. Keets hatch with leg problems that you hope is just straddle legs so you do everything you can to correct it until it finally becomes clear the keet isn't getting any better and needs to be put down. Some keets die without any problems that you can see. Some are too weak to completely hatch so you help them knowing better every time you help because those keets die anyway. Brooders have to be at the right tempature. Keets can't get wet. They can't be in drafts.
Guineas are not like chickens ... you can hold them and pet them while they are young but soon they become kinda on their own. They have their own schedule. Their own agenda. They can be so funny and so stupid at times. They are loud! Very loud at times. Then there are times that they are so quite that you wonder what they are up to so you go check it out and they are dust bathing. Oh yea .... dust bathing. Be prepaired to have holes in your yard, garden, flower beds because they love to dust bath. I made mine their own little dusting place that had a waterer and everything but they don't use it. Be prepaired to not be able to talk to others in your yard because the guineas have decided that the person you are talking to is a stranger and you need to be warned. Even though you have told them a hundred times the stranger is your MOM!!! They go to your neighbors house thinking they live there too and your neighbor hates them. Then they can't find their way home. They run up to the stray dog that just entered your yard like they know it but it doesn't turn out good .....
Males and females ..... you can't tell who's who until they start talking. The females make a two sylibal sound that sounds like "buck wheat". The males can only make a one sylibal sound however the females can make the one sylibal sound too. Then there are some that don't say a thing and you have no idea what it is until it lays an egg or not.
All in all, I love my guineas and wouldn't trade them for the world. I love taking care of them and being around them to watch them and to laugh at them. My family and friends come out to sit in the evenings just to watch the guineas. There is more to guineas than a lot of people know so I am glad you are doing your research before you decide. People say they can free range and roost in trees at night. I tried that my first year and lost every single one to preditors. So a coop or some type of safe place for them at night is a must. You will need some type of coop or run to keep them in for about 5 to 6 weeks to train them where home is also. They need higher protein feed than chickens and sometimes the feed maybe hard to find. How much land are you on? Are your neighbors close? Do you have dogs? I can't trust my dogs with the guineas at all and they have been around them their entire life. I just can't take that chance.
So .... with all of this said ..... and I know others will put in too but guineas are fun, they control ticks and other bugs, they are funny, they make you smile, but there is work in keeping them, keeping them safe and healthy.
