Yes, L'Or are aluminium pods. Not a huge range but £2 for 10 when they are on sale (often) and £3 usually. Cheaper in bulk online. They taste good and even look much better than others. I never had a problem with the plastic ones myself. I have used Cafepod and they work fine.
Not sure what you mean by excellent? I have tried many alternatives including the Dualit versions. The vast majority are plastic and crack in the machine. I haven't tried L`OR, but are they aluminium pods? The other issues with plastic is the non-recyclable nature of the pods.
There are some excellent compatible Nespresso pods on amazon and even in supermarkets - L'OR are brilliant and Gourmesso are also very good.
Nespresso all the way... They also do decaf pods of course.
Dolce gusts all the way. You can use ordinary milk with this machine too - I warm mine for 30 seconds in he microwave and then use the grande/grandeintensi or preludes capsules. I' a bit of a coffee need having lived in France and Spain but I get my hit every time and they even do a decaf pod - truly wonderful