Aight
There is no doctrine of notice in registered land. Don't get confused about this. If you don't treat the tests for notice and actual occupation completely separately you will get hopelessly confused.
What we do have in registered land is this fairly wide carve-out for the interests of persons in actual occupation - these will continue to bind. This exception is limited because it doesn't apply if the person was asked about his rights; and it doesn't apply if the right wasn't reasonably discoverable.
There are similarities between the factors you would look at to see if a buyer was on notice; and those you would look at to see if a right was reasonably discoverable. But its important to appreciate that the two tests aren't the same. In particular: they work differently. In unregistered land, if a buyer is on notice, that's it: the right binds. In registered land, FIRST the person with the right needs to establish actual occupation - once he's done that, he's got a prima facie right. If the buyer of the land doesn't want him to have the right, the buyer will have to show that the right wasn't reasonably discoverable. Note that the test is different ("not reasonably discoverable" is more obviously objective than notice) and that the burden of proof is the other way around. For your essay you will need to think about the similarities and differences between the "notice" regime in unregistered land and the "actual occupation, but not if the right wasn't reasonably discoverable" test in registered land.
Schedule 1 and Schedule 3 are doing substantially the same job. Schedule 1 is where you go if the land is being registered for the first time. Schedule 3 is where you go when land which is already registered is sold.
To illustrate, When unregistered land is sold, lawyers still go through the unregistered land conveyancing process, but the buyer must register the land within 2months. In this case you are looking at the unregistered land regime to see what rights survive the moment of transfer, and Schedule 1 to see what rights survive first registration. Of course, the seller of the land could apply for registration before sale himself, in which case the buyer would be buying registered land, so you look at Schedule 3.
They are substantially the same, though Schedule 3 is slightly wider in some respects.