Cactus



Succulent

the first is a Mammillaria mystax.
sorry i don't know succulents so i can't help with the rest.

G'day... I'm with Lewis ... Mamm mystax for #1, #2 looks like an etiolated Graptopetalum paraguayense... would like to see a pic of the flowers when they emerge to confirm.. #3 is a sedum , don't know the species though... I've got like this in my rockery, and it's spreds rather quickly. #4 is Sedum morganianum, commonly called donkey's tail.

CP

#3 is Sedum rubrotinctum (albeit etiolated .) also called Christmas Cheer. goes red and green in bright sunlight, yellow flowers.
agree with id on Graptopetalum paraguayense .common name Ghost plant
AND agree with #4.