oh boy, we did two bathrooms which had concrete shower walls. I used a circular saw with a concrete blade, sledge hammer, crowbar, mesh cutter, and lots of sweat! i did not want to just hammer the heck of out it. I would have damaged tiles in other parts of the house as the whole house shook with each blow! Once you get one area out, the rest comes out in sheets. You can use a crow bar to separate it from the studs. Have plenty of helps to take the trash out. good luck and keep the bar stocked for later...

I would be more inclined to have a narrower physical walking entrance to the kitchen with a counter or bar height pass-thru than a wider walking entrance. Think in terms of the cook. Suppose you have a room full of guest and in full view of your MIL you "accidentally" drop her Filet-mignon on the floor. While a half wall would have saved you the embarrassment and allowed you to have retrieved the delicate morsel and with a quick wipe of both it and the floor, deposited it upon the bed of blanched swiss chard, saving the moment. I mean, after all, it's not as if you hadn't washed the floor in the last week or two,........is it.

Walls running perpindicular do not necessarily indicate a load bearing wall, but could signifigantly have importance supporting the ceiling joists, as matt stated, a 40's house more than likely is underengineered.I've seen 2x4 joists on older homes, so removing a fairly large spanned section will result in ceiling sag. Your joists might also splice on the wall depending on span. Load bearing concerns bracing off the wall as a means of support to the roof framing calc'd for snow load, roofing weight, etc.This is commonly referred to as live load.The wall is generally supported below by a footer if on a slab, or piers if on a crawl space/basement.The wall supports the roof framing above. If you have short spans with no bracing to the roof framing, your joists aren't spliced on the wall, and the ceiling joists are structurally sound to carry across without wall support, then you would be safe to remove them. The best bet is to pay, (usually around $300), for a structural engineer to come out and give you a detailed inspection of your project.

BTW: I hope you're planning on saving and probably reusing those doors. They are worth a fortune as are those gorgeous door knobs.