In answer to your three points, plus your further point, with apologies to Moussemoose and Bertrand who can more than hold their own ...
M4Dad
"Say the EU introduce a law or a policy that a lot of people don't like. How do we hold them to account for that policy? Short answer is, we can't. They are not democratically responsible for their actions"
In practice, the EU works very efficiently to make sure that there is a very broad consensus on the adoption of any new legislation and it is highly unusual that anything goes through the EU system which the key member states (including us) do not want. So in your scenario, these issues are resolved long before any legislation is actually adopted.
Sorry but in reality, the popular myth of a democratic deficit refers back to the old EU in the times when Member States had absolute veto powers. The modern EU has an increasingly strong democratically elected parliament whose role is to balance the individual interests of the individual Member States. Of course this frightens national politicians who see that the EU has a democratically represented will.
So the EU is a much more sophisticated construction than most people acknowledge and this is causing problems with how to deal with the repatriation of powers to London. We do not have the same checks and balances that the EU system has.
see Peter Millar's article here.
And btw, we played a very significant role in creating these checks and balances.
So unfortunately, even the most simple over-view of the EU, shows that these legitimate concerns are in fact wholly unfounded.
As for Greece:
I am afraid that the good citizens of Greece have been betrayed by their own political elite, not that of the EU. You simply cannot blame all of Greece's problems on the EU. Greek citizens were sadly misled by their national politicians.
The EU wanting to erode the Nation State:
quite clearly, the purpose of the EU is to enable nation states to share powers and competencies in order to be more efficient and effective. Which would you prefer? To be part of a leading global trading block of 28 nations whose influence is direct and effective across the globe, where we pay a significant part in directing its policy? Or would you prefer to be a single Nation State with lots of good ideas with no ability to command influence on the global stage?
Sovereignty would come with a considerable price. (We have maintained our collective sovereignity in the interests of pursuing our collective welfare, not only in matters of trade, but environment, food safety, environmental standards, animal welfare etc etc).