Wow... not sure how I missed all this! lol
Here is my two cents... or three or four.

First off, blue you asked about how to know what scripture is relevant and what is not.
From a biblical view point...
2 Timothy 3:14-17 says this.
14But as for you, continue in what you have learned and have become convinced of, because you know those from whom you learned it, 15and how from infancy you have known the holy Scriptures, which are able to make you wise for salvation through faith in Christ Jesus. 16All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, 17so that the man of God may be thoroughly equipped for every good work.
Note that Paul tells Timothy to "Continue in what you have learned.."
And that "All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness."
Now you have to keep in mind that during this time there was no New Testiment. So any time the apostles refer to scripture or the law (the hebrew word Torah) or "The prophets" it always refers to the old testement. Those were the only scriptures they had during that time.
So by this sense the bible itself interprets itself (which is how it should be) All scripture.
I understand some people follow just new testement, but personaly I don't agree with that. I can, however, respect that and agree to disagree. None of us are going to get EVERYTHING right, especially not me.

You also mentioned wemon not working and slavery. Again, I think you were pretty much on Rebel. Again you have to keep in mind the setting of the day and culture it was writen. That was how the culture worked back then. I don't think it is wrong for wemon to get jobs, however it wasn't wrong in the bible times either really.
The wemon were working pretty much all day, just like everyone else. But during those times they had little time to do much else than raise their children, cook etc... but they did grind grain and such things as well.
As far as slavery goes, biblical slavery really isn't quite the same as modern day slavery either. In biblical times a slave was payed for his work and (suposed to be) treated basically as a member of the family or a guest. The bible does talk about men who don't treat their slaves right and that it is wrong. Also, after seven years all slaves were released, so it was more like a seven year work contract that you got paid for but couldn't get out of in a way. (unless of course you get into bond servants but they chose to be slaves for life and that is a whole other issue)
As far as being gay goes... I don't want to offend anyone but I draw a line there. If anyone knows what happened to Sodom and Gamorah and knows it happened largly because of gay activity and other immoral activity you know the bible speaks plainly against this kind of behavior. So if you are looking from a biblical viewpoint there is no exscuse for being gay. Bow if you don't claim to be a christian, then I'm fine with you being gay because you have freedom of choice that God gave all humans.
Also, you asked how do you know God loves man and women the same. First off you need to understand that "love" to God is not the same as love is to us. Infact the bible tells us that we can't even comprehend the greatness of His love for us. But it never states anywhere that God loves either gender more or less than the other.
Man was created first, and women was created from man so man is the "dominate" gender if you want to put it that way, but this really only goes for in a mairage. However, God instructs the men very specifically to love their wife and to take good care of them. Even though mairage is lead by the man, it's a partnership. If either wife or husband gets thinking they are incharge and the other must do what they say,t hat's not right, because a man who loves his wife is not going to push her around and such. I believe that is partially why God gave that commandment.
There are some things in the bible that only apply to Jews, some that only apply to men or wemon jews and some that only apply to the priests! There are a total of just over 700 commandments in the bible I believe and most of them don't even apply to us because of the above selections.
In america we have over 2 bilion laws... so it's not like God has burdened us with tons of laws.
There are others that are out dated. When Jesus came it says he did away with the "hand writing of ordinance."
Since He died as an eternal sacrifice for ALL sin the sacrificial system is no longer needed from the old testement and the things related to it.
The ten commandments, however, certainly are still rellevent. To point out the distinction...
The laws of Moses were writen by moses on paper (paper is a symbol of something that passes) and put in a pocket on the outside of the arck of the covonent.
The ten commandments were writen on stone ( a symbol of something timeless and unpassing) and were written by GOD's own finger and placed inside the arc of the covonent.
So, if I don't have you all totally confused by now... I've done better than I feel like I have. haha
Now to address your question Clave, honestly I don't think the lack of religeon would stop many wars. You see wars are mostly waged for personal ideals and gain. While often times people will use some religeon to back their war, it's not the root of the issue. And if someone really wants to justify killing others I think they will do it with or without religeon.
The crusades, for example, are strictly against christian principles which shows you either the people behind them were really messed up or they had a hidden agenda and used religeon to back their effort.
Unfortunately many religeons have this problem, but the bible says you will "know them by their fruits." So if someone is doing something that is against the bible (assuming they claim to be a christian) you know they are not following God like they should be.