Nikaah & Marriage Issues

Advice to give up masturbation

Q: I am a severe porn and masturbation addict. I have been struggling with this for many years. I used to watch porn and masturbate 2 times a day. It's a 10 year addiction and I am still suffering from it.

Now I am facing real consequences in my life. I have lost my studies, my career has been down hill almost over and now I feel like the divine consequences are getting more severe. It's like Allah is slapping me and each slap gets more severe. I am being exposed, humiliated, troubled also completely lost. Please make dua for me. 

Using a duff in a wedding function

Q: A person I know is getting married, so they are hosting a party where we will gather and eat. The duff will also be played in the party. The party will be women-only, but I'm having some doubt on the duff part. 

Is this within the boundaries of permissibility to use the duff? Also, I think they will use some speakers so that the duff is louder.

Paying mahr in installments and wife claiming her mahr from husband's estate

Q: Is it allowed for the husband and wife to agree on terms/installments for the payment of mahr? Example: I'll pay you 1000 every month for 2 years. Is this OK or is it better to pay upfront one time even though it is less? 

If the husband dies, can the wife claim this remaining amount from the inheritance?