Whether four acres (about 1.8 ha) is enough for two cattle depends on your land. If it grows good grass, yes, certainly, in the summer. What will they eat in winter? If you're really lucky with the grass you could make enough hay or silage, but you'll probably have to buy it in, especially if your winters are long.
If your land is dry, or acidic, very wet or otherwise poor, it might not be nearly enough. My cattle winter on heathland (very acidic sandy heather land) in southern England, and they are a bit overstocked at one to four or five hectares (10 or 12 acres). In summer I can get away with one to a hectare (2.5 acres) on marshland -- but that floods in winter (actually, it's nearly under water now, in this year's British Monsoon).
You could do bottle calves, as Fortitudinous Skeptic suggests. Alternatively, you could buy yearling steers (castrated males) and rear them for a year or two -- you'd have less time to wait till your freezer was full. Have two of different ages, and you'll stagger the killings.
Dairy bull-calves are worth considering and will be cheap, but if they're extreme dairy they won't come to much. I would not keep a dairy breed as a bull though -- they can be savage bug*ers. Bull-beef tends to be lean, but you may like that.
When you do kill them, make sure they are hung properly -- three or even four weeks. Far better flavour, and more tender. We have our beef hung and processed by a local butcher, who joints it and vac-packs it for us.
Or just one cow, with its calves. If it's a heifer calf, sell it, if a bull calf, eat it (castrated, or he'll get his mum -- they have no shame). At any one time you'll have the cow, latest calf, year-older calf and one ready to sell or kill. You'd have to send her to a bull, or AI her. And if she's reasonably milky and well-fed, you could get some milk off her too.
You could fit a lot more sheep or goats on that land...
If you're squeamish about naming your food, don't do it at all -- stick to beans... Being eaten is a noble and worthy end for a beast you've loved and treated well. Meals in our house begin "For whom we are about to receive..." (or would if we weren't sceptics too).
Actually, this is a bit of a problem with cattle, even for hard-hearted farmers like us. You eat them at two or three years old, just when they're growing up and getting friendly. Lambs and chickens are eaten much younger, when they are still irritating adolescents.
As to breed... Commercial dairy or beef breeds are highly bred to milk or grow at very high rates -- but need very high feed intakes, and often have health problems. More traditional, low-input, healthier breeds will probably suit you much better. If you are thinking of a house-cow, a traditional dual-purpose might do, such as (thinking of UK breeds) Lincoln Red, Dexter (small and sometimes tricky), Shorthorn, Normande (French, and beautiful), Irish Moiled or the milkier ones of the British Whites we keep. South Devon is another one (different from the American Milking Devon, which is really a dairy form of North Devon, a beef animal in the UK). Angus might do -- or dairy calves sired by beef bulls, such as Hereford or Angus crosses. Beef breeds would be OK if you don't want to milk (or have very strong hands): Hereford, Highland, Luing, Galloway, North Devon, Salers, White Park, Welsh Black etc. Do talk to your neighbours.
Incidentally, Charlie P is not really correct to say that cattle are poor producers of protein -- it depends on the system. They are not as good at converting feed into protein as some other animals, but the feed for those animals will be grain you have had to buy. However, cattle can use good grassland far far more efficiently than chickens or pigs -- and cattle, sheep or goats will still thrive on poor grassland where chickens would starve. Grain may be a more efficient use of grain land, but not if you feed it to animals first -- only if you eat the grain yourself! Cattle is a far more efficient use of range-land.
Are you prepared to give up all your time? No holidays, no weekends...? No money.
Apologies for long post, but you did ask...