Shoe customs in Japan/China?

Question:

I know that cultures in the east are very meticulous, and thus wear different shoes in different rooms: indoor slippers and bathroom slippers, even in public bathrooms you put on special rubber ones I think. But I never have been there so don't know how widespread the changing of shoes in public restrooms (i.e a mall).

I have started studying Chinese so I plan to head east at some point to live for a time so I can practice my Chinese and maybe eventually Japanese, but I would want to spend a year out there.

Now I was wondering about all this because I have gigantic sized feet. Not just average big "western" feet compared to Asian feet, but really huge feet for any human standard, size 17 mens and I'm barely 6 feet tall so they are also very disproportionate. I can't find shoes in the west, let alone would I ever find them in Asia where people have much smaller foot sizes.

So two questions: what size would I be over there (17 mens US, 16 UK, 51/52 EU, but checking online my size is, literally, off the scale over there), And second, how would I deal with this in a practical way? Like, should I carry indoor slippers with me everywhere I go (since none that would be available there would even fit my toes... :\), and what about for restrooms and stuff. I mean, would I have to carry a backpack simply to carry two pairs of shoes?

Finally, would I get gawked at by everyone in a subway and stuff? I get stares where I live, so I'm used to the ''freak show'' status, but would people think badly of me or would the just be shocked at the sight of such extremely large feet?

my girlfriend is a 13 womens (11.5 mens) so same goes for her :

Answer:

I buy sandals let the heels hang over.
Shoes off when entering a house and duck. After 4 yrs of college went home to japan and unthinkingly walked into the house with out taking of my shoes slammed my forehead on the beams and sat down on a sofa and everyone was looking at me and I said what?

In bath rooms they have different slippers than house slippers.