Hi Safehaven,
If you do get sheep, they will be very lucky sheep! For years, I've kept a few pet sheep on about 4 acres. I've never found the need to poo pick or harrow the small amount of sheep poo that goes over that large amount of land. You may find the same. However, if they have an area they like to like down in or spend time in (mine have a big field shelter) then you will want to keep those areas clean so that they don't like in muck and attract flies, leading to fly strike.
If you get sheep or lambs that haven't been bottle-fed or tamed by someone else, you may have some difficulty getting to know your sheep in such a large area. While some will come to bucket, others may not. Depending on the breed, they may or may not be "flighty".
Therefore you may want to create a smaller enclosure to start with. When I first got sheep many years ago, I had 5 Dorper cross ewes. I put them in a relatively small enclosure to begin with until they could stand me being in there with them, take food from a bucket, then from my hand, etc. I then made the enclosure bigger and bigger until they had the whole of the place. I got them used to being fed inside 4 hurdles, so that when I did have to trim their hooves they were easily "caught".
Some people divide their pasture into 2 or more sections for the purposes of keeping worms down, which I am sure you will read about in the books. However, as my sheep got older they kind of figure out where they would be in summer and where they would be in winter, when the ponies ate down half the grass anyway, so they developed their own natural rotation.
While I don't poo pick the field for them (I do for the horse poo) I do keep their shelter relatively clean. When they were in smaller enclosures I poo-picked in order to reduce flies, make sure their fleeces had a good chance of staying clean, and because it was an activity that put me near them without directly addressing them. They started following me around as I cleaned up, in fact.
Eventually, some of them became incredibly friendly, while others were just "tame" in that they would be lured by buckets and put up with me doing work on them.
Hope that helps.