Asia is huge so I'm generalising a bit here. Did I miss anything?
  1. You are required to remove your shoes
    No shoes in the house period.
  2. The first thing they'll ask is if you have eaten
    Food is a big social thing here. Whether you have or not is irrelevant.
  3. The second thing they'll ask is how are your parents doing
    Knowing your parents is irrelevant.
  4. It's polite to bring an edible gift along
    Fruit and baked goods are typical offerings. You may even get served these same food.
  5. If you're new to the house, follow their cue. Sit where prompted, and inform/ask if you would like to move
    It's just plain courtesy. The best place to be in is the kitchen, of course, but only if you're invited in. If you can help, do so. Otherwise, sit, sip and start small with the talk.
  6. The visiting elder persons will survey your home without permission
    It's law. They WILL open every room door and poke their noses through your things uninvited. Therefore, clean, hide or destroy incriminating things prior.
  7. Coming unannounced will throw them off
    Hosts like to be prepared and make sure that they have something to offer you. It's a dishonour for a guest to leave a home unfed and dissatisfied.
  8. You may be served on Corelle
    This is tops for non-relation guests, or when they want to impress. Separately, Corelle last forever.
  9. Tea will be Lipton, and coffee Nescafé (or whatever's the local generic equivalent)
    If they really know you, they'll bring out the good Chinese or Red Palm brand tea.
  10. You will leave the home with leftovers
    The only way to outwit them is by finishing all their food--which they will cook too much anyway, which brings me to....
  11. Don't finish 'all' the food
    While you'll be complimenting the host on their good food, they'll mostly think you've been starved or just plain greedy. You will also be served the best parts. You can always eat the leftovers or grab something else later. Do not finish all the food even if they insist (any cultures that are OK with finished food?).
  12. That said, eat 'everything'
    Especially the ones where it takes the longest/most ingredients/hardest to make/not made traditionally that way nowadays (they'll tell you, they're very proud of it). You know how much you're welcomed in such homes when they go the extra mile.
  13. Use the utensils provided, or not. If you're a noob, it's no shame asking for a fork and spoon.
    We use hands in my family for rice and dishes. If you don't ask, we just assume you'll do the same.
  14. Offer the elders first dips. Eating is communal, and it's fine if someone offered you a good piece from their plate
    We may spend quite a time offering someone to eat first. No, you, you go ahead. No, I insist; I'll be right with you--after you take the first bite 😈
  15. Don't be offended when interrogated about your weight and/or relationship status.
    Suggested by @makpuiki
  16. Have I mentioned how much food is a big thing here?
    If you have dietary concerns, please inform the host prior, subtly. Like, "I'm on antibiotics so can't take milk with that." Nothing like a served food going cold and uneaten.
  17. That said, gluten-free, vegan and paleo requests will just leave them confused
    It's hard to be any of those here, though such options are available more often nowadays. You have to be prepared to partake what you can and deftly decline others.
  18. Compliment something in their home
    If it matters to them, you'll know it.
  19. Thank the host for their hospitality by acknowledging their effort
    Despite the food, it's not really *about* the food. It's an honour to share their home with you, and for you to spend your time with them.