Pretty sure the first is Anacampseros rufescens, there are a number of varieties. See: https://davesgarden.com/guides/pf/go/70947

They're supposed to be purple, that's normal for this species. They're doing great.

Thanks guys for those IDs! Definitely: - Oreocereus trollii - Pilosocereus pachycladus Maybe: - Gymnocalycium anisitsii Why maybe? because sometimes my plant doesn't match well with plants on google G. anisitsii is a quite variable taxon, some varieties have very pronounced stripes or patches of co...

The first is Oreocereus trollii. I think the last one is Gymnocalycium anisitsii.

Put a bird cage over it.

Lobivia acanthoplegma was the closest to a match that I could find, but it doesn't quite fit - I think it's more likely a hybrid.

Yep. There are so many of these hybrids that it's often impossible to determine which you've got if it's unlabeled. I really love the color of this one, though, wish I knew its name.

What the Roundup web site says about that: "Thanks to this plant's hardy nature and extensive root system, it may require a second application to wipe it out completely."

I think they're being over-optimistic.

Looks like a Lobivia, now lumped into Echinopsis.

Quackgrass is a real pain, it will come back. Germination inhibitors won't help, since it spreads by rhizomes. However, if you put down a deep mulch, the rhizomes will run just under the mulch and can be pulled out easily. I found wood chips worked well for this, I'm sure gravel would do the same. A...

Pot culture is very different from growing in the ground - excess water is drawn away by the surrounding soil in the ground. In a pot, only the force of gravity drains it, and it's a weaker force than the adhesion of water to the soil. Soil in the bottom of the pot remains saturated until the plant ...

No - it's a Euphorbia, but nothing like frankiana. Maybe E. anoplia.

Yes. some of them aren't in very good shape for transplanting but it can't be helped - you risk much more severe losses by not getting them separated. If rot should get started in that mass it would be devastating.

Yes, cuttings should work fine. Cuttings of this species root easily.

I searched and found a counterpart of your plant: https://davesgarden.com/guides/pf/showimage/26329

Fasciation, commonly called cresting, can occur in any plant. What you have is clearly a crested plant which has partly reverted to normal growth, which is not unusual. Yes, it's Ceropegia mixta, better known by the older names Orbea variegata or Stapelia variegata.