Cactus help!

Here’s some shots of my cactus. I know some of you have to be experts. I need some help.

The first shot… this plant. I don’t know what it is. Is it even a cactus? It’s sitting on the window sill, and you can tell that the leaves (or whatever they are) are growing well pointed away from the window. Even smaller branches are coming off of it. Meanwhile the part that’s in the sun seems to be doing worse. This is a cacti right?

Next pic is of an aloe plant. I think window is an ok place right?

Pic after that. These two seem to be doing alright. I think.

Next one: I don’t know if the plant on the right is ok. The “leaves” seem to be falling off little by little. some of the flowers at the top are dead and dried, but some are fine. It’s been replanted, and it looks ok, but the “leaves” thing freaks me out. They fall off and dry out. The cactus on the right, I think is fine, but will I know if it’s not?

next photo: I think they’re fine. The plant on the left grows white cobwebs on them. Is that good? It’s not a spider, right? It looks like cobweb. The middle one is my fave, it looks good and seems happy. The one on the right, I think is doing ok. Then that stringy thing just popped out and it looks like there’s a leaf or someone on it. WTF is that?

Last photo: The plant on the left… that little thing, I have no idea if that’s happy or not. Is it? The one in the white pot… it was green, but now the tips are red, perhaps from the sun. Is that ok?

Cactus are in the desert, so sun is alright, but these seem to be like domesticated or something. Their maintenance seems high for plants with low maintenance.

The big question. How often do I water them? I’ve heard once a month. Then I read the little tab that comes with the plant, and it says to water when the soil is dry to the touch. Does it rain every day in the desert? The soil dries up after a watering in a few hours. It’s dry. What do I do? Water it again? I have no idea if I believe the expert who wrote that little tab? Which means “water every day” since the soil is dry every day, or do I not?