Hi Everyone,
I'm new to cactus and hoping you can help me out with some ID, I've numbered the pictures.

Also a question about #7, I received this as cutting about 4/5 months ago. I let it calloused over for about 6 weeks before potting as it was winter. I potted it about
2.5months ago (start of summer). I have not watered it very much at all (scare of rot, as that happened to another of mine). It has grown no roots yet. Is this normal? How long should it take to root? Should I water it? It sits outside on our patio with arvo sun.

Also for #2 I'm planning to repot it, should I separate the 3 of them now?

Thanks for your help 😊😊
I'm in Australia

1, 7,8 look like some kind of Myrtillocactus
4,5,6 look like mammillaria
2 looks like a cereus???
3 is ferocactus of some kind.

Yes, water it - just once though. Damp soil will encourage roots.

@Aeonium2003 I agree
2 is juvenile Cereus forbesii
3 I think Ferocactus horridus
4- maybe Mammillaria haageana
6- maybe Mammillaria nivosa(though its not supposed to be solitary)

Re #4
I purchased this one and it was labeled as Mammillaria 'Elegans'. I suspect it may be M. haageana 'Elegans", but photos of M. haageana are too variable for me to trust that completely and therefore I've never entered it in the database. You might compare yours to photos of M. haageana. I agree with Stefan that it's a possibility.

The photo is from several years ago. It's a 10" column now.