OP, you sound like you're being super thoughtful and I think that's wonderful of you! And I think (you've probably already thought of this) that it'd be good to learn a few terms in their language like "welcome" and "good morning."
I'm borrowing trouble here and I hesitated to mention it, but not knowing your background, I'll bring it up. I was born and raised in the U.S. but I've seen a lot of culture clash in my parents' marriage because of their very different backgrounds. If your MIL and BIL are not used to the American culture, they will likely (not for sure, because I obviously don't know them) have a more old-fashioned view of gender roles, depending on where they live - big city vs. small town.
And I don't know your marriage or how you breakdown the responsibilities. Just be prepared that there are some things that they might expect you to do that in the American culture, someone might assume the adult child should do, and not their spouse. For example, in past generations in the US, if one didn't get a thank you card for a wedding gift, the bride would automatically be seen as lacking in manners, even if the gift-giver had been a friend or relative of the groom. Nowadays, if a friend of the groom gives a couple a wedding gift, and there is no thank you note, depending on generation, the groom might be the one seen at fault. Likewise, if one visits a household where both spouses work full time jobs outside the home and one sees a lot of dust in the bathroom, one might say "Oh, the wife really isn't tidy" or one might think "some adult in this house needs to clean."
I don't know if your MIL and BIL will expect you to be the one who does all the cooking, and look down on you if you don't cook every meal and let your DH cook. I don't know if they'll give you strange looks if you shovel the snow from the driveway or mow the lawn. Just remember that you are in your own country. And it's fantastic that you are thinking of them and wanting to be welcoming! But that I've witnessed situations where a marriage is great, and then when the relatives arrive "from the old country" suddenly the spouse isn't as Americanized as they used to be and tries too hard to do things to please their family members and get their spouse to assimilate into the old country's culture. Be prepared to say "Well, we're in the U.S. And in my culture we do things differently." Especially with regard to your children.
My mother wasn't raised with rules like "no feeding honey to children under age 1" or "don't introduce too many allergens into a child's diet when they're very young" so even though she raised me in the U.S. and I am raising my kids here, she was often disregarding "modern Western stuff" that she didn't respect.
Please, let us know how it goes.