First of all, this is not the best place to ask questions as this is a majority non-Muslim website, and we don't take Islamic advice from disbelievers, only from Islamic scholars. If you have a question, I recommend googling the question and then typing either "islamqa" or "islamweb" or "askimam" which are Islamic fatwa sites 0nline.
1. Masturbation is a sin in Islam, as Allah says in the Noble Quran to not come near zina, which is what masturbation does. The Islamic scholars state that if not masturbating will lead you to commit greater evil such as fornication, then it is better for you to commit the lesser sin (i.e. masturbation), but you should train yourself to avoid it all together.
Prophet Muhammad (s) recommended Muslims to get married as soon as possible, so you should seek a spouse asap, and you should recite ayat 25:74 in the Quran which is dua for marriage. If you can't get married, then you should fast, as the Prophet (S) said fasting helps control temptations, and there is a huge reward for fasting.
so to answer #1, "with no hands involved," I have no idea how you'd do that, but if you're using some other object to stimulate then it is the same thing and is *****.
2. No you're not allowed to masturbate after marriage either.
3. I don't know the answer to this, you should look up this question on islamqa or islamweb.
4. Is what allowed? You cannot have premarital relationships with the opposite gender..obviously.
5. If you're married to more than one woman then you cannot have a threesome, this is ***** in Islam, you can only approach each wife individually for intimate relations.
6. Regarding if one wife can look at the other, I don't know the answer to this, I imagine it's not okay.
The information I posted is from the Islamic scholars from the aforementioned sites.