@cpaartist - I am 100% sure that the porch was originally an outdoor porch - I opened up part of the wall in the laundry room and found the original wood siding and openings where windows originally were in the bedroom. Sadly they did a very poor job enclosing it. The back bedrooms were originally some kind of mechanical workshop - I haven't figured out exactly what type yet. There is a large barn door that runs along the exterior wall in the hall - they enclosed the wall and left a single door in behind the exterior barn door - I would like to restore that and have it open to a patio. There are a couple of houses in the neighborhood that are very similar to mine. I believe that the part of the living room with the fireplace was a later addition as well - the other houses don't have that. I love old houses with all their quirks and mysteries!

Here's a mockup on your to-scale (ish?) drawing of a new bath that keeps the toilet in place, similar to what benjesbride was talking about. I didn't bother creating anything new for the laundry, but her drawing shows a very nice idea! You could also leave the NE corner open for a dining area or study area and erect a wall at a later time for a bedroom if desired, as you suggested. The measurements are estimates but should be pretty close. The bathroom would be approximately 6x10.5. Theoretically, you could extend the bathroom farther to the east and extend your kitchen another foot or two, but I worry about creating a pinch point between the kitchen and the staircase. Incorporating that central post into the island could also create a tight squeeze between the island and bottom of the stairs depending on the actual measurement between the two.

Your space looks so narrow and with your back to that wall when cooking and opening the oven, I wouldn't want anything protruding from that wall at all. Not knowing your style and art being so personal, it's hard to make meaningful suggestions, but I would get 3 large, colorful posters for that wall...there are so many choices, for all budgets. these are all from Great big canvas and all of their art can be ordered in different sizes. I would go large and since it's in the kitchen and so close to the stove (cooking odors, steam, oil, etc would affect fine art), I might not even frame them or mount them, but hang with poster putty and replace when/if they need it.

You have tons of options, but one is to do a shallow plate rack to display some of your larger platters or boards like the one below. You could do a collage of prints and pictures (maybe some framed family recipes) or just even a large single print. You also have plenty of room for a display cabinet if you have items you'd like to display and don't mind moving the buffet you now have on the wall.