Re: more UKIP nonsense
I'm not sure your argument makes much sense. We can tax things that effect companies who are resident in the UK for tax purposes (Windfall taxes / bank taxes etc.). It's much harder to do that to companies that are resident in other tax jurisdictions. Particularly if they are using the rules of the Single Market to trade within the EU. I'm no tax lawyer and I haven't looked at this legislation, but Tim Worstall makes a decent argument as to why it may not comply, and will quite possibly end up being decided by the ECJ in several years time.
Having dismissed his argument, you then go onto some sort of attack, possibly on UKIP, possibly on Worstall, though you don't specify. And it's not relevant to the article.
It's possible that the UK, being the second biggest economy in Europe (although that may depend on how you measure it between us and France), has a lot more negotiating leverage than Switzerland. And can carve out a better deal. Particularly as we run a trade deficit with the rest of the EU (a surplus with the rest of the world) - and there would be lots of political pressure from big EU companies wanting to keep access to the UK market. Espeically as the only plans for Eurozone recovery seem to be based on exporting, rather than stimulating internal demand, and for that they need markets willing to import.
On the other hand, the irrationality of the way the negotiations are currently being handled with Greece suggests there's a second option, where the EU plays the rejected lover and decides collectively to punish the UK for the insult of leaving. Despite doing more damage to its own economy in the process than it does to ours. I believe if we do decide to leave, that the agreement has to be unanimously approved by all member states, the Commission and the European Parliament. There don't seem to be many genuine Federalist believers left in politics at the national level, but there are many at the EP.
It's interesting that Cameron has not even put it on his list of things to try to negotiate, any restrictions on free movement. He's decided it's just not possible, so there's no point asking, he's better to try to negotiate on things he can actually get. One of which is to try deal with the technical differences between benefits systems. Many EU countries have contributory systems, so poorer migrants have much smaller incentives to go to those places. Where as we have in-work benefits for which you don't need to have contributed beforehand. So that could be acting as an incentive for people to come here, and take low-paid jobs - and price down the wages of the lowest paid. There might be a deal there, as Germany has similar issues.
However I presume you were attacking UKIP rather than Cameron. Myself I'm no fan of UKIP, but I can understand why they've become a political force. If Cameron were to win the election, attempted to negotiate and got nothing, I'd be very tempted to vote to leave in a referendum. I don't buy the argument that our economoy couldn't thrive outside the EU - although the EU has some nice advantages. But there is a major democratic problem, and rather like Scotland, if people feel that the downsides of the political compromises required to stay in the union outweigh the upsides of the trade it promotes, then it's time to think about leaving. As democracy is really important. The Eurozone crisis proves that the voters of the EU do not feel that they are one people - whose taxes and laws should be shared - and that means if the EU pushes integration past a certain point, it will lose all legitimacy. UKIP argue that point has already been passed. On that, I think I agree with them.