Yep, found pictures of S. sarmentosum and I have to agree that is what the mystery plant is. I thought the other plant was the moss rose I planted last year making a comeback, but now I don't think so. I think I remember this being around last year in addition to the moss rose and the S. sarmentosum. It just has never grown as prolifically as the S. sarmentosum.

I don't recognize the first plant but the second sure looks like a mulberry to me, probably bird planted. I suggest you take it out now before it's more established.

I suggest you visit the Hydroponics Forum as they may be more help. But I also suspect that a rather large outdoor weed may have challenges adapting to a different growth system. You might be more successful starting with a much younger plant which will grow indoors. Perhaps ask the Hydro folks for suggestions. http://forums.gardenweb.com/forums/hydro

Thanks for all your help! #1 does look like a Dischidia nummularia when I googled a pic, and #2 is definitely a Hoya Linearis! They are both growing very well and look great in my flat. I own a flower shop in London and ordered them a selection of mixed hanging plants through my supplier in holland, loved them so much I took them home. Have orderd some more for the shop now as the supplier thought the second was a type of senecio, thanks to you guys I put him straight