1# very strong spines! About the size of a fist! Spines are white, reddish brown to black at the axil! After light misting spines turn translucent with visible red rings! This is one of my favourites

#2 every time I try to id this I find the old man but I'm not convinced! I have a small old man and the spines seem to have a yellow/brown tinge in them especially at the top whereas this one has very glassy white spines and no hair exept at the axil theres a little tuff of white fuzzy hair/spines

#3 Notocactus Warasii? Came across this one while searching notocactus for another species! Thanks to kenizon

4# no idea!