1. could be M. haageana, not sure about the subspecies.
2. May not be a Mamm at all. I cannot see anyaxls from the photo you have posted.
3. This is difficult. I haven't seen a Mamm like this quite so heavily spined, and it is difficult to gauge the size of the plant. At a guess, I would suggest maybe M. jaliscana in one fo its many forms.
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Chris43, moderator