(A) Is it really possible??? do you mean a unified state? how will handle full right of return?
No, I mean a true federation in which people are able to live, work, do business etc where they want, e.g. USA (or, in other words, EU acquis!).
TC may get to have a non-sovereign component state on say 25% of the land, with state officials being elected by only the TC community, but this should only be able to deal with internal governance issues and not issues such as foreign policy, immigration, security (e.g borders) etc etc. The strong central federal government should of course represent the communities on a basis that does not discriminate among citizens, i.e. 1 person 1 vote.
(B) In theory could be acceptable to many TCs accepted Annan 5 but the 18-20% land distribution should be assesed by independent international experts to confirm the exact percentage pre 1974 as there will be many disputes dating way back to the 40s 50s 60s to ownership etc
Possibly. But I don't think anyone disputes the population percentages. It is also well known that TC were generally poorer than GC even well before any trouble began - partly as they were having large families and hence depleting their per capita wealth. If I remember correctly, according to the British-run land registry the land ownership of TC in 1960 was around 12%. In any case, given the population, I think 20% would be an absolute maximum.
The percentage of land to be returned needs to be sufficient to make it worth all the trouble, risk etc of a solution, from the GC point of view. Otherwise, any plan will fail. In the past (short-sighted) GC politicians accepted something around 25% for TCs, but that was on the basis of a true federation (as above) and it was achieved under the indirect threat of war by Turkey.
Obviously, the more "sovereignty" the TC state wants, the less the land it will be able to have. In addition, because of the EU and the projected integration (e.g. EU army etc), GCs are now feeling increasingly secure and are less worried about Turkey doing another "peace operation", which makes them more demanding in negotiations.
At the same time, as time passes, Turkey's negotiating position becomes worse, as the stakes for her EU accession become bigger. Accordingly, the longer Turkey waits for solving the problem, the more concessions she will have to make. It is in her interest to make a serious offer to GC now and get it sorted.
If this does not happen, I can see a scenario in say 10 years when Turkey might be begging for ANY solution in order to get in the EU. Eventually, this may lead to Turkey withdrawing the troops, dissolving the "TRNC", handing back the stolen land and demanding that the 1960 agreements are adhered to.