D'varim - Ki Seitzei - 2015

In beginning of the Parsha we have 

The beautiful captive that he is not allowed to marry right away and if he doesn't like her after 30 days he can't sell her and you can't put her to work.  (i'm guessing that means that she just goes away free) - negative commandment - do not do

A man marries 2 woman, one he hates, one he loves.  He cannot give the birthright to the child of the one he loves, if the firstborn is the child from the one he hates.  - negative commandment - do not do

If a man has a wayward and rebellious son you must bring him to the elders and they will stone him.  positive commandment - to do

If a man commits a sin worthy of death you shall hang him but do not leave him hanging there.  negative commandment - do not do.

Do not hide from returning lost items of your brother.  sounds negative, but then it says 'you shall surely return them', maybe both positive and negative.
Though the pasukim continue and it says at the end of pasuk 3 that 'you cannot hide yourself'.  Leads me to believe that this is all part of a negative commandment.

Pasuk 4 very similar, not sure why this case is separated out.  Here is a case of helping someone who needs help, the case before was someone who lost something.  Yeah, but couldn't that all have been included into a single category?  Why do we need to separate them out?

21:14
Why does the Torah say that you cannot sell a woman captive with money (bakesef)? Does that mean that you can sell her with a non kesef transaction?  Ie, trade her?  The pasuk could have not said anything about money, it could have just said you cannot sell her, period.

Why is selling with money specifically bad?  If the Torah wanted to protect her from being abused it could have left out the word bakesef entirely.  Trading her would be mistreating her in a significant way.  Why is selling her with money the problem here.  

Following the discussion of the woman captive, the Torah tells the story of a man who has married two wives.  He hates one and loves the other.  How could a man marry a woman that he hated?  Doesn’t sound like a Torah thing to do.  Or if he loved her and then hated her only later why didn’t he give her a get and get divorced?   From the pasukim it sounds clearly that first he hated her and then he had a child with her.  Why did he have a child with a woman that he hated?  And then not only that if she had the child before the woman whom he loved had a child, even if he hates her, her child still has all the first born rights.  

Okay so what?  What we’re saying here is I would have thought that because I hated her I could have not given her child the first born rights?  Is that a rule that I wouldn’t have known?  Ie, the first born child gets the rights, no one says that if I hate the woman it gives me an out and I can all of a sudden choose who should be considered the first born.  what's meaningful about this?

22:22

Why does the Torah say 'and you shall remove the evil from yisroel'? It says this numerous times in separate paragraphs at the end of a specific act that is needed to be done.  Aparently this is something that needs to be said.