The first two are definitely a weed, though I don't know its name. I have done the same as you, let that plant grow into the large sprawling thing you have there in hopes that it was some sort of volunteer beauty, but no, it's not. It has flowers, but they are insignificant, and the plant, while not as unattractive as some, is just not anything you want in your flower bed. The good news is that it is not a particularly noxious weed. At least around here (Southern CA) it doesn't reproduce that wildly. Just pull it out. The third photo looks like some kind of wild geranium; that is, a true geranium, not a pelargonium. At least around here, those are quite nice to have.

It's got a Malvaceae look - like some sort of hibiscus or mallow. I expect you'll get an answer fast but if not, take a pic when that bud opens, and post it as a follow-up

I believe it is purslane. If it is, it IS edible. Here is a link that might be useful: Is this it?

Crabgrass? I think I can deal with that. I bought the weed-b-gone that is NOT for crabgrass. Anyway, I always thought crabgrass grew in clumps and laid low, and was very tough. At least that's the kind we had up in New England. Maybe this is a different kind of crabgrass? This stuff spreads loosely, and is not tough. that is, the leaves and stalks are tender.