No DRM, but patents on the machine and the capsules. Enforceability of the patents varies a lot between countries, so in some there are non-Nespreso capsules, in others there aren't.
No DRM as far as I can tell. You can make your own pods with simple kits which are basically just an empty capsule and some foil you stick on the top.
Indeed. Lots of supermarkets and coffee brands in the UK sell their own Nespresso-compatible pods, often much cheaper than the "real" ones.
In Germany, Nestle tried and failed to ban sales of unlicensed pods: