Welcome to the forum. Get ready to meet some nice people.
In addition to the Henderson Chart that PortageGirl gave you, this link takes you to a breed selector tool that can help narrow your breeds down a little.
My Pet Chickens
http://www.mypetchicken.com/breedQuestions.aspx
The site gives quite a bit of info on the breeds also.
Feathersite
http://www.feathersite.com/Poultry/BRKPoultryPage.html
In addition to the breeds shown above, I think you should investigate the sex link varieties. Those are specific crosses of certain breeds that can be sexed at hatch.
What I think you are planning is to have two separate combinations of coops and pens that the chickens will be locked up in at night and that they will be free to range over your 5 acres during the day. PortageGirl is right. Your climate plays a very big part in the answer. The -5 for a nightly low helps, but storms, snow, and ice also comes into play. How predator proof your coop/pen combinations are also matters.
The general rule of thumb used on this site is that you need 4 square feet per chicken in the coop along with 10 square feet per chicken in the run. There are several different components that make up this area. The 10 square feet per chicken in the run assumes they are confined in that area. If your set-up and climate is such that they can range on your 5 acres for most of every day, that limit kind of goes away. If they are going to be confined for significant periods of time, it applies. Why this is important is that chickens confined into a small area can get bored and start pecking and picking at each other. This can lead to cannibalism. Space is important. More is always better.
I may miss some, but I'll run through some of the components that make up the 4 square feet for the coop. There is not a set square foot that goes with each component but it is a composit. And different breeds and different individual chickens react differently. There is not guarantee that if you meet this rule of thumb you will not have problems or that if you exceed it that you won't, but it is a proven guideline that works most of the time. The actual number of chickens also matters. You need to have enough for the components to apply. If yo only have two or three chickens, you probably need more space.
Part of this 4 square feet is the boredom factor. It assumes that the chickens are not allowed out in the run at the crack of dawn but may spend some time locked in the coop itself. That could be that you don't let them out at dawn in the summer since you sleep in. Or it could mean that the weather is so bad they can't go out.
Part of it is that you need room to set up the feeders and waterers so they are not under the roosts. Chickens poop a lot while they are on the roosts. You don't want them pooping on their food and water and they can project that poop a ways. They also need access to the feeders and waterers. You generally want all your chickens to be able to eat at the same time or the less dominant ones may not eat enough. They do need access to feed and especially water when they wake up.
The nest boxes may not count in the square foot calculation. Chickens are basically ground dwelling birds. If the nesting boxes are high enough that the chickens can get under them, they do not take up usable space in the coop. You do want to make sure the chickens cannot poop in the nesting boxes while roosting, but you can do that with overhangs if necessary.
Part of the calculation is poop load under "normal" poop management practices. Chickens do put out a lot of poop. It needs to dry out or it can stink and lead to disease. It can also put out a lot of humidity and ammonia, especially if it is wet, both of which are bad for chickens.
Chickens handle cold very well as long as they are not in drafts but have adequate ventilation, especially while roosting. I'll suggest Pat's Ventilation Page to read up on this.
https://www.backyardchickens.com/web/viewblog.php?id=1642-VENTILATION
I'm not going to go into detail on predator-proofing your runs and coop. I will mention that raccoons and others can climb very well.
Assuming your run-coop combinations are predator-proof (and that is a big and probably erroneous assumption) and your climate is such that the chickens can range on your 5 acres practically every day, there are somethings you can possibly do to violate the rule of thumb. If you can feed and water in the enclosed runs and not in the coop, you free up space. In essence, just use your coops as sleeping areas and emergency storm protection. Obviously, put your nesting boxes high enough that they do not take up floor space. And use something a little more intense than normal poop management practices, either a scrapings board or something to catch the poop while they are roosting so you can remove it on a pretty regular basis.
You have another complicating factor, two separate coops. Chickens are social animals and tend to hang together. You may be able to train them to sleep in separate coops, but that would probably mean confining them to the coop/run combo you want them to use for about a week. I'm not sure you are going to get a lot of benefit out of that smaller coop/run. It could be a good grow out pen or a place for a broody to hatch and possibly raise chicks, although I am in favor of a broody raising chicks with the flock. But that is a different topic.
I don't know if I have helped much. If you meet all this, I would not have serious concerns with putting 12 chickens in the larger coop/run, but the more restrictions you put on them, the smaller that number becomes.
Good luck!
