The mix looks too dense, IMO. (Many commercially produced mixes are.). Most folks here will recommend "cutting" that mix with a substantial amount of gritty material to make the mix more free draining. Using a pot lacking in drainage is a recipe for disaster. If you are particularly attached to that pot and wish to use it, drill (or melt if it is plastic) some holes in it or plant them in a pot that does have holes and nest it inside the blue one. (Though you will still want to thoroughly drain said pot before placing it in the blue one.)

That 1st one is most likely Hylocereus undatus (pitahaya/pitaya, dragon fruit). What you see is the way it grows (and that's why I got rid of one I had :) It grows big, spiny, with those hard aerial roots. It needs to have support and be tied to contain it. I would grow it again only if I had lots of space, or (even better) if I lived in warm climate, where it would get plenty of sun and heat it needs to produce fruit. You can look up how they grow them on 'pitaya farms', trained up on trellises. There are also photos available of plants grown in containers and kept quite neat - if they are real. I am not sure if I would invest space, time and effort in my zone. Just to have a big, very prickly plant...Obviously, it is your choice to keep it or not. If you get it to bloom, flowers are very nice. They are big and IIRC, nocturnal. This plant is used a lot as a rootstock for exactly what you purchased - grafted plants. It is very vigorous and probably easy & inexpensive for that purpose. It grows easily from seeds if you purchase fruit in a grocery store.

If you are redoing the floor, I think the time to take out the half-wall is now. If you do it later, you will have to patch the floor. Does it separate the entryway from the living area? I like having some separation, but if it were me I might replace the brick planter with a framed half wall. No more brick and no reminder that people in the 70s thought that permanent built-in planters were a good idea. I'd want some contrast between the wall and the brick, but I don't have enough personal experience with whitewashing to know whether you can get that using the wall color on the brick.

@John The Home Depot Design Center's installers are not certified, though they plan to be soon. The woman I spoke to on the phone told me they were, but, when I went in and spoke to the manager I bought from, he said they weren't and there was confusion about that because they had been certified until certain changes to the corporate structure at HDDC were finished and now they need to reapply, or something like that. So I knew they weren't certified, but thought they were as good as certified. That's why I got the five year extended warranty (because the lack of the Miele-certified installers meant that Miele would not double my warranty through them to 2 years (which they do when Miele-certified installers are used. And, yes, I think what you say about third-party installers might be correct. I know that HDDC has their own installers, which they tout, and I was impressed by that (but not so much now). The second set of installers they sent with the replacement machines were very good.