2) If you with green mean wind and solar then yes it means expensive because both have a low capacity factor and intermittency problems which means that either coal, gas, oil og nuclear have to be there as a backup. They, of course, need to be calculated in just as things like decommission which isn't being calculated in for wind and solar but is for nuclear. In other words, green cost as it's calculated is not the true cost.
3) No green isn't the most practical solution exactly for the reasons mentioned in 2). Sure you can provide a little here and there but you cant actually build a flourishing economy on wind and solar and there isn't a single example of that being the case. With oil, gas, coal and nuclear you can. Nuclear is too expensive which leaves us with fossil fuels.
So I would claim that your 3 reasons lack reality :)