The Russians are going to push for the application of the wartime to its fullest extent, but Britain might oppose the Russians going all the way to Gallipoli and Tenedos/Imbros.
I m pretty sure that the British would prefer to have a greek-controlled Gallipoli Peninsula in addition to greek Imbros and Tenedos. The Russians would also prefer to keep both locations. Basically, it is down to you to decide what balance to keep. Either russian Gallipoli/ greek Imbros/Tenedos or all of them greek seem plausible. I doubt though that the British would allow Imbros and Tenedos to become russian and the Russians cannot force the issue.
3/ Inland Eastern Thracia: if I'm not mistaken, the wartime agreement said nothing about inland Eastern Thracia. Letting the Sultan keep it seems improbable. Greece could covet it, but it's certainly less attractive that the Gallipoli peninsula. Russia could push for the annexation of the whole of Eastern Thracia to give strategic depth to her annexation of Constantinople. Could this lead Russia to give up her claims on Gallipoli, Imbros and Tenedos?
I think if it comes to choose between inner Thrace or the Gallipoli peninsula, the Russians would choose Gallipoli in a heartbeat. Russia doesn't need inner Thrace as it only adds management problems. Constantinople in any case is defended by the Catalca Line
https://upload.wikimedia.org/wikipedia/commons/d/d2/Borbe_kod_Čataldža.svg
In any case, Constantinople will be a russian outpost, a fortress to defend the Bosporus Straits, not a core region. To defend it in depth in the current turkish Thrace borders will be difficult and would require huge investment and several armies. Gallipoli can also be turned into a fortress by simply fortifying the 6km-wide isthmus of Bolayir. The fact that in OTL Sazonov didn't give a damn about inner Thrace is telling.
Also it is good that you didnt go forward with the greek attack towards Constantinople, because in OTL 1914 and 1915 Venizelos was very mindful not to provoke Russia but accomodate the Bear was much as possible when it came to claims to Constantinople. Being a very capable diplomat, he would need to have a stroke to needless provoke Russia.
4/ The eastern shore: if kept out of Eastern Thracia by Russia, Greece is indeed going to push for more annexations on the Eastern shore, all the way from Smyrna to the sea of Marmara. But I wonder if the Russians wouldn't prefer to see a weakened Ottoman/Turkish State rule on the Eastern shore rather than a British stooge. (This question is also linked to what will happen in Anatolia regarding Kemal, the National movement etc.).
I think so as well. The Russians would prefer the asiatic shore to be turkish and the British to be greek. A possible accomodation may have been the OTL Venizelos proposal that the Turks could keep the asiatic shore of the Dardanelles (
Sanjak of Biga) and Greece keeps the area around the Bandirma-Smyrna railroad and more lands in the south.
In this case, the asiatic shore stays turkish, while it is detached by the rest of Turkey by the greek zone that extends to Pandirma.
In that case, Greece would look to compensate with lands further south than the OTL Smyrna Zone, where greek interests clash with italian ones. To accomodate the Italians, the Italian Anatolia may be pushed further south and east. In tha senario, Greece may get the
Aidin Sanjak (in yellow) where there are large greek populations and the Italians get permanently the
sanjaks of Burdur and Antalya. Antalya is a strategic location after all, that may serve as entrepot for the central Anatolia.
5/ How Russia will deal with her new province of Thracia-and-the-Straits? It's great to finally restore Tsargrad to the true faith, but then what? The majority of the population (Greeks, Turks, Bulgarians) will hold no particular love for the Russians (the Armenians are probably the most well-disposed towards the Tsar's rule). How do you rule this "kingdom"? Encouraging Russian/Armenian immigration? But I guess this is a problem for tomorrow, not for the Paris Conference.
Well, as I said before the inner part of Thrace is useless for Russia. Constantinople has a mixed population that due to economics alone (a major port or service hub) will have a christian majority very quickly, without any ethnic cleansing. The Greeks are a known quantity in the Russian Empire, with hundreds of thousands them in the Black Sea ports and Caucasus. The Greeks of Constantinople are not rebelious mountaineers, but an urban population that was well used to be part of a multi ethnic empire- a muslim empire that is. I think they would welcome russian rule, for both bein co-religionists and providing them with a huge imperial market - the Greeks were burghers and heavily involved in trade, banking and industry.
The same applies for the rest of the christian minorities of Constantinople that were also well used to be part of a multi ethnic empire.
In the other hand, I think it is extremely plausible that if Russians get the Gallipoli peninsula they will expel the turkish population. In March 1914 there were 8,220 Turks, 16.137 Greeks and 1,190 Armenians. As soon as the war started, the Greeks and Armenians were expelled. That leaves only the ~8,220 Turks for the whole peninsula. Russia can turn the peninsula into a purely russian " island", very easily and very quickly. The point is that if they don't expel the turkish minority they would have to call back the previously expelled greek majority. That doesn't give room for russian settlers in this strategic outpost. Instead, they can use the previous atrocities to justify turning the peninsula into ethnic russian: they only need 25,000-30,000 settlers in total.
The sliver of land that connects Gallipoli to Constantinople is of limited value to Russia, so I doubt they would give much thought to settle it, as there is no point defending beyond Catalca and Gallipoli.
problem also remains that annexing more of the aegean coasts means that the Turkish minority in Greece would expand.....otl during the 1919-22 war around 5% of the Greek population were Turks, adding more of the Aegean coastline means around 10% to 15% turks, which is not exactly a good thing for the Greeks if they want to remain democratic, or the Turks if the Greeks decide to say 'what is democracy?'
I think a population exchange will take place regardless the timeline's POD. Ever since 1914, the Ottoman policy makers had decided against having a christian minority in their country. In 1914, even with a neutral Greece there was an expulsion of something like 250,000 Greeks from Anatolia. In the east, after the russian collapse, the liquidation of christian minorities continued after the armistice. I dont see how a population exchange is to be avoided under these conditions. The only other option is to have a unilateral liquidation of the remaining christian minorities, even after this more damaging ottoman collapse, something not plausible. Not to mention that in OTL with Turkey in a much much stronger position, there wasnt a single turkish policy maker that didn't like the idea of a population exchange. Certainly Venizelos would go for it.
Overall, I don't see how a population exchange is to be avoided.