There is a lot of contention on this issue on the left. Broadly speaking much of the left takes a position against the EU being a project of the capitalist class
arranging European "unity" on a basis of mutual capitalist
interest. I think this position is pretty much ok.
However, things go awry when the same people try to offer an alternative and get stuck at national strategies. This can range from "radical" Keynesianism to blunt nationalism. All such roads are a dead end however, since capitalism is a global
system and as such national roads away from it will lead to disaster: bankruptcy, military invasion, police state... you name it.
So, instead we have to realise that our positive
alternative starts at a continental level. On this level we can start
to build towards a better kind of society and transcend the evils of the inherited capitalist society, overcome the rule of value and start to begin a society based on the rule of planning to human need.
Thus, instead of merely attacking the EU, communists ought to engage with this given playing field and incorporate it into our own project of a united European working class, striving for political power as a class
As for your questions:
1. I think we should generally oppose referendums. Despite their aura of being democratic, they in fact are not. First of all, we do not create the question on the ballot, the elite do and they'll use that position for their own agenda. Second, it might feed into the idea that people actually have a say about anything in society, while they do not. The Irish referendums on the Lisbon Treaty are a case in point: Just hold a referendum again and again until you have the "right" answer.
2. Britain is
a part of Europe, despite that culturally you seem to have this habit of talking about "us" Britain and "Europe", as if it was on a different part of the world
But seriously, I merely repeat what I've already said: We should not buy into the official pro-Europe agenda, but claim
our own pro-European agenda. This not being a far away and abstract thing into the future, but by engaging directly
with the given playing field. I.e. demand democratic rights in the EU institutions. This will act as a lever to organise the working class as a class
on a European level and let them claim Europe as opposed to falling back into nationalist romanticism.
3. A tricky debate indeed. I'm leaning to "yes" as it would mean more (political) unity and thus a common enemy. That said, it is a given that the Euro should actually survive its current existential crisis.
4. I support a European Democratic Republic. That is, a state where the people are sovereign and rule. The "USE" advocates are coming from a more pro-capitalist angle
5. If the referendum should come, we ought to participate in it and campaign for our cause. I don't see the point of the Tories using a whip. Against whom? Themselves? They will, after all, be the people starting the referendum!
As for my political affiliation: I'm a member of the Committee for a Workers' International (the English section of which is the Socialist Party in England & Wales) and consider myself an Orthodox Marxist.