Having worked in the US on a tourist visa will create large headaches for you. The best thing to do is bring all of his paperwork to an attorney to see how to proceed. As long as same sex marriage is recognized in the country you do it it like Canada that could be a first step. But need to consult an attorney.
This is a question for a Venezuelan attorney. Generally you are allowed to stay out of the US as long as you are a US citizen. If you are a green card holder it is not advisable to leave the US for a period over 6 months. You should consult an immigration attorney.
Need more facts to answer this question. In order to qualify for an E-1 visa you need to be from a certain designated country. It is difficult to extend or change from b2 to b1. My best advice is for you to bring all of your paperwork to an immigration attorney to assist you.