How much worth is the land that Poland annexed with the help of Stalin?
Idk. Maybe we can subtract that land value (despite the fact Poland owned 70k m2 of land in the interwar period than after WW2) from the millions of Poles who were forced into the Red Army, exiled to Siberia, had their land confiscated even if they were broke farmers as owning a small field or a few bags of grain would be enough to get you thrown in prison or even shot, died in Katyn or the gulags, as well as having a puppet government for 50 years with out government in exile living in London or Paris... We'd end up in the positive as you can see..
Actually it wasn't thanks to 'Stalin's altruism' that's for sure. The unfair deal that Poland received was a result of the Yalta Conference - Stalin, FDR, and Churchill with only Churchill truly protesting and demanding a fair deal for Poland, a democracy, fair elections, etc.
Also, France and Russia received German lands as well... As you know, Europe was divided into spheres of influence between the West and USSR with the 50 year cold war resulting as of that, along with 5 decades of puppet regimes for Poland. Yes, we'd love to get reparations for this - subtract the land fine - we'd still be in the black.
How much worth are the hundreds of thousands of lives of the former inhabitants that got killed when the Russians and Poles deported them by force?
Stalin's and the Allies orders based on negotiations in Yalta, Tehran, Paris, Moscow, etc. He demanded 4 million slave laborers. Stalin installed a puppet government in Poland that didn't represent the interests of the Poles at all. The Brits wanted to help Poland, especially Churchill (who was pretty vocal although took little action but at least had the guts and morality to launch Operation Unthinkable - aka 'a square deal for Poland'), but FDR didn't really care (he protested but also took no action) and they agreed to make the already installed commie puppet government more democratic although there was no way to enforce this and of course Stalin didn't care one bit about democracy. Churchill even asked Stalin to hold fair elections in Poland and his operation which unfortunately never took off sought to regain Poland from Stalin.
If the Germans didn't leave they'd end up in gulags (which many did anyway) or would be killed by Polish puppets at the orders of Russians and the UB - who would kill the Poles if they didn't comply. What would you do if someone put a gun in your hand and told you to kill the 'xyz-ist enermy scum in front of you' with a pistol to the back of your head? Many Poles had good relations with their German neighbors. Even the Polish 'volksdeutche' was put into camps or exiled. We were unable to resist this given the grave situation and utter destruction of the country in the years following WW2. Stalin and his bootlickers installed loyalists who killed AK members and other Poles who wanted to have a government that represents the people and not a puppet regime subservient to Moscow and Stalin. Among those killers are people like Michnik's brother, Solomon Morel, and much of the UB and especially their leadership. As the Kruschev thaw was taking hold across the USSR (especially in E Europe like in Hungary, Czechy, PL,, etc) and the crimes of the aforementioned individuals and people like them were exposed as well as the brutality of Stalinism with the result being the Polish October and later the March Events. Poles especially hated the Muscovites - the Polish Jews who left during the war, went to Moscow to kiss Stalin's a$$, and came back with the Red Army to enslave the Polish population and do all those things to Poles and Germans alike. These guys made Gomulka and Co. look like the good guys. Many of them assimilated and pretended to be Polish Catholics so as not to arouse suspicion, some emigrated to the West in the late 60's/70's, some went to Russia or the other parts of the USSR if they were considered loyal enough, etc. It didn't take long for the early Muscovites and Polish UB Jews to realize that even though Stalin earlier ordered them to be cruel to the Poles for being loyal to the AK and government in exile, it didn't necessarily mean they themselves wouldn't share the same fate - death, gulags, or be put in the middle of Siberia with an ax and a pack of matches and told to build a camp.
Anyway we're not talking about the Russians/USSR, we're talking about Germany. But yes, I would like Poland to receive reparations far more than from Germany as they've committed even more crimes against Poland and Poles for a far longer period too. Nonetheless, Poland is focusing on what is feasible at the moment which is obtaining reparations from Germany. Perhaps in the future, rapprochement between Poland and Russia will take place and perhaps reparations for things like Katyn will be part of that discussion. Till that happens, and the ball is in Russia's court to make the move if they want better relations as they can't blame us for being better, the situation between PL and RU will remain regardless of which government in PL is in charge. Perhaps if a more open minded, less 'Russian occupier' focused individual is leading Russia this may occur.