US Immigration from Mexico

Hello there! I m a 23 years old guy from Guadalajara, Jalisco. I am going to process my tourist visa for the first time. I have heard that a citizen friend or relative in the United States can write an invitation letter to the United States to the person who wants to apply for the visa and in this way it is easier or more likely that they will grant you the visa, my question is, What does the letter need to say? Can it be a letter of invitation to work? Can a person with a criminal record but already clean write this letter? Any recommendation?.
Thanks for reading. I await your answers.

How long does it take lately between getting an NOA2 and getting an interview date in Mexico City? I'm anticipating getting my NOA2 sometime later this month or in February (I filed in April 2021), and I really want to know how long it takes until you receive an interview at the Mexico City embassy. On Mexico k1 pages I'm in, I see some people only took 2 months to get theirs, but some people took 8 months to get theirs. Is their an average time it has been taking lately? Thanks!

Hey guys, we got our visa approved last Wednesday (12/22/21) and are still waiting for them to return our Visa. We were just wondering if anyone else interviewed around that time got their passport back yet and how much the holidays are going to affect it.

Hello everyone - My fianc has her interview for the K-1 visa in February, however, for personal reasons we need to stay in Mexico for the next few years and then go through the process for a CR-1 or IR-1 visa.

Are there any particular issues we should be aware of? Will USCIS hold it against us that we cancelled our K-1 visa process?

Someone from the forum who can help me happens that I move and change my address in USCIS, but a few days ago when reviewing my case online, they said that they scheduled an interview for my adjustment of status and that they sent me a letter to follow up on the directions, so I called USCIS to ask why that letter did not arrive and they told me that that letter was not sent to my old address so now I do not have access to the mailbox of my old address every time that house was sold, so I feel lost because my interview was already scheduled for January 18, I don't know how I can get a copy of that letter if someone can help me resolve my situation. I appreciate it.