My suggestions would be:
1. M. bombicyna
2. M. backebergiana perhaps - needs more light!
3. M. backebergiana
4. M. elongata
5. M. elongata
6. M. zeilmanniana?
7. M. spinosissima ssp pilcayensis
My reasons for 2 & 3 are that there are only about 10 radials and a few centrals, though it is difficult to see in photo 2.
For 6, the flowers are forming and I hope they are going to be purple red.