Neat project! Congrats! I like the ARXX blocks but the nearest source is a ways away from me and no one near by uses them. I will be using Polysteel brand which fairly recently added another style block to their lineup. It is 13 inches wide over all and 2 ft tall by 4 ft long. Concrete is 8 inches thick with NO waffle grid and NO post and beam, just 8 inches of crete. It has steel "nailers" on 6 inch centers recessed 1/2 inch below surface.
I reproportioned my master suite to acomodate an integral number of blocks to reduce waste. It is 31x35 OD now.
Are you using any of the PanelDeck/LightDeck/whatever horizontal analogs to ICF for any ceilings or floors? I'm using PanelDeck for the basement ceiling which gives me a floor for the space above. I found out about the new block too late to use in basement which poured 2 days ago so cast the walkout basement walls in place (12 inches thick with 9 ft ceilings).
I'm just the reverse of you... You have 1 buried wall and three walls with windows in your "basement." I have 3 buried walls and one window wall.
We put a tad over 50 yds of 4000 PSI crete in the basement walls. The header beam over the window/door opening (16 ft wide) got 5 pieces of #8 (1 inch) rebar in the bottom and a couple #5 (5/8 inch dia ) higher up. The beam is 23 inches tall and 12 inches thick.
Keep us up to date with your project, it is quite interesting.
Pat