That's a tall plant, #1, and looks likely to be as you said, but I'm not great at distinguishing the karwinskiana/voburnensis subspecies.
As for the 2nd.....what a great plant, only solution is something like a dustbin lid!
....and a touch of weedkiller for the oxalis. I use a glyphosate solution, and just paint the top leaves with an art paint brush. Doesn't seem to affect the main plant, though I was worried about it leaching out of the dying plant, but its supposed to be rendered ineffective when it gets to soil.