I am married but I also have some homosexual desires. I know someone who does too. Are we allowed to be unclothed before each other and hug and feel as long as we don’t spill any semen in vain (motzie zera)?
Also, my wife and I like to do different positions – standing, sitting, doggy style etc. Is that forbidden? Can my wife and I watch porn to enhance our sexual pleasure? Can a man watch porn alone if he will have relations later on that night? Thank you.
There is a general Torah commandment: "Be holy for I the L-rd your G-d am holy" (Leviticus 19:1). The things you mention are not holy and should be avoided. Besides being considered unholy and brazen, they lead to spilling semen in vain, which Jewish Law defines as a very severe transgression (Shulchan Aruch, Even HaEzer 23:1-2) . You should know that the clear drops of liquid that sometimes appear at the outset of sexual arousal is also considered spilling semen in vain, causing spiritual damage on a very high level.
Hashem sees everything we do, so a person should cultivate a feeling of fear and shame in His Presence when engaged in the unholy acts you list, including the homosexual behavior you mention.
The halachah states that marital relations should be performed with the man facing down on top of the woman, with the woman lying on her back under him, facing up. In other positions, the gymnastics and force of gravity causes the semen to spill out of the wife before it is absorbed.
Watching pornography is also not holy, in addition to violating the serious Torah prohibition not to go astray after one's eyes (Numbers 15:39). It is also prohibited to engage in marital relations while thinking about other women, and this occurs when a man conducts relations while having visions of pornography or other pictures of women in his head. The holy Kabbalist, the Arizal, warns that the pleasure one has from improper sexual activity (ענג) turns into a plague (נגע) bringing many ill consequences upon the couple and their children, may Hashem have mercy.
You will find it helpful to read over the "Laws of Marital Relations" http://www.jewishsexuality.com/the-laws-of-marital-relations-part-1 by Rabbi Mordechai Eliahu, posted on the www.jewishsexuality.com website, as well as "Keys to a Holy Union" http://www.jewishsexuality.com/keys-to-a-holy-union by Rabbi Leon Levi, and the many other important articles, and questions and answers, posted on the site.