The answer really depends on why you are using saying this. If you are having a conversation with a friend, you would probably say, "Who does the land belong to?" or "Who do you want to talk to?" because those are more informal. However, if you are writing a paper for a class or business, you would want to make sure you use correct standard grammar. In that case, you cannot end a sentence with a preposition ("to"). You must put the preposition before the object ("whom"). So, the correct sentences for a written example would be "To whom does the land belong?" and "To whom would you like to speak?"

If you rephrase the question to include he/him, then select which of those 2 sounds better, that will help you tell which is correct. For example :Can I say ”To whom would you like to speak?”? Ask it as" Would you like to speak to he/him? " In this case, "him" sounds better so you would use whom. Now for example you wanted to see if it should be "Who/whom is home?" so you would rephrase it as "is he/him home?" , and "he" is correct, so you would use "who" to ask "Who is home?" Also, you wouldnt start a sentence with "whom". But as Jmat said, most people stopped using "whom" altogether, which is kind of strange if you think about it. Its kind of like how most people dont know when to use "him and I" or "me and him".

You can, but 'whom' has become largely archaic in modern English. 'Whom' is rarely said in British English and I believe it has dropped completely out of use in American English. It is still sometimes said, but you won't be incorrect to say 'who' in place of 'whom' like the majority of people do. It's your call whether to use it, but I recommend that you only use it for academic writing (if at all).