Labelling can be a problem, especially with old collections.
Plant #1 - its not M. lindsayi, nor even M. cobrensis as the Lau numbered plant has become, following the rediscovery of the original lindsayi. It looks rather like a form of M. standleyi that I have, but not sure.
Plant #2 - might be meyranii or even guerreronis
Plant #3 - looks to me like M. multidigitata, with those pale flowers and straight spines.
Sorry not to be more certain about 1 & 2.