I am planning on marrying a non U.S citizen, what actions do I have to take prior to marriage and after?

As long as the marriage is bona fide, it does not matter if you live in separate places for a while after marriage. You just need to be able to document the bona fide nature of the relationship at the time of the interview. You can get married and file for his adjustment of status on the basis of marriage.

"Is an immigration lawyer needed 100%?" No, but if you are asking these questions you need to consult with one before taking any action. In addition, your question really requires an attorney consultation. It is not a simple question that can be answered on this type of forum. There are many factors that would need to be considered and evaluated. I strongly suggest that you contact an experienced immigration attorney for a face-to-face consultation and give him/her all of the facts surrounding your situation. He/she would then be in a better position to analyze your case and advise you of your options.

It is always best to live with your spouse once you get married if you plan on applying for him. There is a lot of fraud for spouse petitions, and Immigration is often on high alert to detect fraud. Even if you are validly married, not living together is a serious red flag to them, and your petition for him may end up being denied. So, it is probably best to wait to apply for him after you start living together. What kind of visa is he here on? You can always represent yourself in your own legal matters, but it is usually not advised. I compare it to this...you can retile your bathroom floor, even if you have never done it before, but it may end up a total mess and you will have to hire someone anyway. Same thing. And the filing fees for a greencard are not cheap, so why would you risk having to start over again if something goes wrong? Every attorney has their own fees, but you can expect $3k+. For example, I charge based on complexity of the case and how much time I think each individual case will take me. I also offer payment plans to make things easier on you. But whatever you do, PLEASE PLEASE PLEASE DO NOT USE A NOTARY OR NOTARIO! I cannot tell you how many cases I have had to clean up because someone used a notary. They are not attorneys. Just because they work for attorneys does not mean they know all the nuances of the law. And they often don't, which is why people get themselves into a mess from using a notario. Unfortunately not all cases can be cleaned up after a notary messes it up.

A spousal adjustment of status case ("green card" based on marriage to a US Citizen) is a rather complicated and lengthy matter and is best handled with the guidance and help of an experienced immigration attorney. There are both government filing fees for the series of petitions required as well as fixed fees charged by the attorney who handles your case. Contact us or another colleague off-line and we/they will explain the process in greater detail and itemize the costs involved for getting such professional assistance.

Since you're living in separate states I would strongly recommend that you work with an immigration attorney to ensure that you present your case properly to USCIS. It can be done, but it isn't easy.