That's a good paper you got there AmoAttack, on a very interesting topic.
I can't speak for other countries, but being French, I can certainly confirm and refute some points you made about this country.
Immigrants have also had a difficult time assimilating themselves into European culture.
A bit off-topic, but that might be one misconception I wanna mention: outside Europe (and I hear that a lot here in the US), people tend to think that the whole process of developing an actual European Union in the past decades has really altered Europeans' way of thinking, so that they actually feel they belong to Europe first, then to their country. But really, in France (and I'm pretty sure it's that way in the other countries), people will never tell you that they're European before being French. If you mention that they belong to Europe, they'll say "hmm yeah, I guess we do, but it doesn't really matter...". Even with the Euro and the virtual disappearance of borders, it'll take much much longer for this nationalistic feeling to weaken.
On one side is the culture of their parent’s countries and on the other is that of their new nation. They are often at a loss, and do not know what to do. Many European citizens add to this sense of distress, and pain, amongst the immigrants. They do not consider the immigrants to be true Europeans, despite the fact that many have been born and raised in Europe. They often complain about the burden the immigrants put on the economy of the nations, and other such reasons.
I believe this is very true. Wherever they live in Europe, it's very much a challenge to be accepted by the local population as one of them, even if you were born there and speak the same language without any accent. At least, all of that fits the situation in France, no doubt.
Immigration greatly strengthens the European economy, for several reasons, such as decreasing the unemployment rates, and stabilizing the population. Many jobs that are not taken by natural European citizens are taken by immigrants, which is beneficial for the economy, in that the immigrants have jobs while the national unemployment rates go lower.
Again I can only speak for France, but unfortunately this is not the case at all there. Because each country has its own economic system, what might be true in the US for example (which would obviously be badly affected if all the immigrants decided to leave all of sudden) doesn't necessarily apply somewhere else. In France, the unemployment rate started increasing in the late 70's but mostly in the 80's because of unfit immigration policies that allowed large waves of immigrants to come to France unchecked and settle there without any potential work opportunities. In France, you can't really say that "they're filling the positions that the citizens do not want to take". Unemployment has become so bad for 25-30 years because France has welcomed more and more immigrants without offering them any professional prospects, while at the same time offering them a comprehensive social coverage. In France, you can almost afford to never work at all, especially if you have children, because the government showers you with social allowances, unemployment benefits and family support funds. Of course, you can't live like a millionaire with that, but you certainly survive and "exploit" the system (and I'm not talking about the immigrants only here, many French citizens live this way). While that might sound ideal to some, it really messes up the whole system, because you have a country with high unemployment, a high level of welfare payments and sickness benefits, less and less retirement funds for workers about to retire (the retirement system is sorta based on "solidarity" withdrawals from every active worker's paycheck), growing animosity between French people and immigrants, political instability...Well, you get the picture.
I know that unemployment is pretty bad in Germany too, and that immigration has always been a controversial topic there as well, but as far as France is concerned, what should be the positive effects of immigration have always been hindered by bad politics, leading to unemployment and cultural conflicts.
I dunno if that helps, these are just some thoughts...