I have never heard 行きたくありません except on a bad morning drama.

Do men use 行きたくはない?

Yes, why not? Men use it too. It's like an obligation thing and that you have force or drag yourself to do a certain job or errand.

I don`t particularly think it`s a gender related thing.
It does have quite a different nuance than just the 行きたくない. If you`re saying 行きたくはない, chances are you`re going to follow it with けど or が.

行きたくはないが、気になる etc

You`re saying that you don`t exactly want to go, but... something or other.

I hate grammar book...they always give these things as "pick which one you like coz they are the same!". Then you talk to some native speaker and they say they have a difference.

All these little "nuance" that you find here and there are so hard to understand for us foreigners. For example I have someone trying to explain me additional uses of は and I really don't see all those differences. I had finally reached the point to kinda understand the "nuance"of a phrase like　私に息子がいます　and 私には息子がいます...but now I find out that I can even say 私は息子がいます...man I wish I could put in a Japanese man what Japanese learners feels like in these cases :p

That is why lessons are taught one step at a time. When it is supposed to go from lesson 1-2-3-4-5, you're at lesson 2 and you picked up a new phrase of lesson 5 standard from an anime or through discussions at a forum, and you get all confused.

Believe me, the more you learn, the more you find yourself getting confused over things. Don't rush yourself, otherwise your interest in the subject will wane very fast.

The most important thing is to completely understand and be confident in the level that you are working on before moving on to the next level. This way, your foundation will be well covered and it'll be less confusing for you.

Have fun and go easy.

Always assume there is a difference. In general, when it comes to simple patterns, there are virtually never two patterns that mean the exact same thing. If they did, there would be no need for another version. Every pattern has it`s own nuance and "rules".

But those are hard to remember at first... So most books resort to listing them all as the same meaning with the hope that as you progress and have more exposure to the language you`ll pick up on the subtle differences. A lot of those differences would be very hard to explain in text without quite a bit of context.
If the book never introduced them at all, learners would be stuck unable to comprehend anything but the simplest set patterns - which isn`t a good thing for a learner.

So,
1)I want to go (plain)=ikitai
2)I want to go (gentle)=ikitai desu
3)I don't want to go (plain)=ikitakunai
4)I don't want to go (gentle)=ikitaku arimasen
5)I wanted to go (plain)=ikitakatta
6)I wanted to go (gentle)=ikitakatta desu
7)I didn't want to go (plain)=ikitakunakatta
8)I didn't want to go (gentle)=ikitaku arimasen deshita
is this right?

I would go with ikitakunai desu and ikitakunakatta desu for those two.