A diversity visa is usually valid for up to six months from the date of issuance. You may enter the US no later than the visa expiration date. If...

If you are a US citizen, you may petition for your fiancé for the K1 visa. Once she arrives to the US, both of you must marry within 90 days and...

USCIS will not accept a late response to the RFE. That may lead to a denial. You should submit a response before the deadline and then supplement...

It would be best to consult with an attorney in private.

You may use the fee calculator: https://www.uscis.gov/feecalculator

It may take weeks or months but if your case is outside processing times, you may inquire with USCIS. You may check general processing times...

Your sister may apply for an extension before her stay expires.

Since you did not file the petitions concurrently, it would be best to follow the instructions on the USCIS website with respect to the I-485...

More information needs to be provided. However, if you meet the requirements for citizenship, you may file. Any adverse factors should be...

It depends on which application(s) you filed and you may check general USCIS processing times online.