What is the meaning of honoring a guest, and is it limited to offering luxurious or available food? Does it include resident and short-term visiting guests, or only travelers? And how should one deal with repeated visits from neighbors?

Honoring guests is a Sunnah (prophetic tradition), not an obligation, according to the majority of scholars. This is done through cheerfulness, and feeding them what suffices them, and it is achieved by what is customary among people. Avoiding ostentation is better for the continuation of honoring. Honoring a guest involves a cheerful face, kind words, and feeding them for three days: on the first day, according to one's means and what is readily available, and for the remaining days with what is present without burdening oneself. As for anyone who knocks on your door, they should be honored with what is available and easy to provide; welcoming them with cheerfulness and kind words is sufficient.