1. Roosevelt was many things. One of the things he was not was stupid enough to seriously believe the Brits would be the threat and that the Soviets wouldn't. 
2. Roosevelt also said "Nothing in politics happens by accident." 
3. The greatest strength of "Liberal Democracies" as opposed to outright dictatorships is, that by the clever expedient of changing figureheads every so often and not openly bludgeoning people with rifle-butts (as much), the governments of these Liberal Democracies give the people the impression that they have something do with what the government does, thus blunting any natural and healthy impulse of the people to "water the tree of liberty with the blood of tyrants." 
1) I cant agree although it may have been Truman who compounded the damage. Stalin new that Churchill was on to him and that both deeply mistrusted eachother. Roosevelt thought that post war the dismatleing of the British Empire best served American Trading/Imperialist interests (maybe) but in the process overlooking the real threat. Rossevelt told Churchill he new best how to handle Stalin and the Soviets. He Like Truman was concerned the soviets shpould join the war with Japan and did not atach enough importance to soviet expansion in Europe believing Churchill was prejudice against Stalin where he had an affinity with this young developing nation.
It was precisely this attitude toward what he percieved to be the conflicting interests of Britain and USA that colouresd his judgement. Remember at the start of WW2 Britain had the largest navy in the world and a quarter of the worlds population were part of the British Empire and its commonwealth. UK, Canada, Australia, New Zealand, South Africa all loyal allies willing to fight to defend the mother country without first having to be atacked. India (including Pakistan and Bangaldesh), Ceylon Malaya, Burma, parts of China, much of the Middle East including Palastine/Israel, much or central Africa and even parts of South America. In short the biggest empire in the history of the world and pottentially looking to take over what Germany, Italy and France had just lost in Africa and the Far east. That is what Roosevelt did not want to go back to.
History proved Churchill right in his fears and reservations as he had been about Hitler.
3)Liberal democracies do not confer power equally or true equality but they do allow for stable competing elites with a high measure of consensus. The process of legitimation does involve some stage management for the consumption of the masses but it is not orchestrated by on individual with absolute power.
