Looks like Solanum nigrum.

It is Costus spicatus, an old heirloom plant. It was popular decades ago and common in older neighborhoods but hardly ever sold anymore. Its a very easy ginger, grows in part sun or shade but needs moist soil. It gets a cone like inflorescence that is orange, not as showy as Costus barbatus but still nice.

Yes, they will fruit this year. They are really good value - I grew a few plants last year and have had my own grown dried Chillies all Winter from a few plants. They are way easier than tomatoes. I always grow mine from seed. These aren't Chillies, they're Hungarian Wax peppers from seed. As you can see by the Hoya in the background they are perfectly happy growing in my porch.

Could be "Mallow neglecta" a fairly common lawn "weed" sometimes misidentified as ground ivy. The "weed killers" probably killed off the plants that were there but new ones appeared from the prolific seeds these things produce. Perhaps this article might be of some help. http://www.better-lawn-care.com/common-mallow.html#axzz4mEYDCWro