If you are single and never married you should indicate that you are single and never married. Yes, it may impact your eligibility for a visitor's...

Call them or email them, or get a supervisor somehow. This is common, and requires the intervention of a human, not an AI program.

Yes, you can file an I-140 even if you are trying to consular process for your DV1 visa, there is no rule against doing so.

It is completely at your discretion which passport you wish to present to the medical provider for your medical exam.

If his green card just recently expired you should file an I-751 for him and he should enter on his expired green card and I-751 receipt.

Check the I-751 receipt to determine if it is expired and you need a stamp in order to travel. Otherwise, it is safe to travel.

Your father and brother are more than welcome to file applications for tourist visas and of course you can invite them to the wedding.

As a rule of thumb, wait six months to change jobs. If your change shows that there never was a genuine job offer for you nor did you intend to...

If you were paroled for in the public interest for humanitarian purposes [you probably were] and you are not in removal proceedings [which...

You will probably need to provide your father's naturalization certificate, and you should also apply for a certificate of naturalization.