Seeing how eu leaders are getting together so much lately, I'm starting to get the feeling that nato isn't really going to work properly anymore

Here are my two stupid questions

1. Is there any obligation that specifies how much support a NATO member must provide if one of its member states' homelands is attacked? For example, in an extreme case, could a country just send one tank and say "we've fulfilled our treaty obligations"? And if troops are deployed, how is the number determined? Couldn't there be disputes between NATO members over the extent of support?

2. How is "armed attack" defined? Does it cover the homeland? Casualties? Base attacks? Is there a possibility that NATO could avoid its responsibilities due to an undefined "armed attack"?