There are no software patents in Europe. I've seen nothing to suggest that European software companies are less competitive. In my daily work as a developer I've not once heard anyone talk about the competition 'stealing our ideas'.
The reason I think software patents are a net negative is that it's the sum of the parts that make a software product valuable. Patenting some of the algorithms used to develop this software product is not going to protect you from the competition in any meaningful way.
Contrast this with pharma where the end-product is simple, often a single easily reproduced compound.
European software companies do [ab]use patents widely - a historically sensitive example is Fraunhofer institute (Germany) and patents on their invention of the mp3 encoding methods; it brought significant revenue for them, making them competitive; and the patent restrictions also had significant effect on the music software&device market.
This is a good example. There is indeed nothing that prevents an EU based company from filing for a software patent in the US (or other markets). This particular patent has likely been so lucrative (~$100m in revenues) because it's so easy to spot infringements.
Depends on the patent office, both the German & European patent offices are fairly liberal in allowing software patents.
The UK patent office is currently harder to get a pure software patent in.
It's certainly possible to get patents on software particularly if it has a technical effect. The UK patent office gives an example of software that improves a car breaking system would be patentable.
The reason I think software patents are a net negative is that it's the sum of the parts that make a software product valuable. Patenting some of the algorithms used to develop this software product is not going to protect you from the competition in any meaningful way.
Contrast this with pharma where the end-product is simple, often a single easily reproduced compound.