Nikaah & Marriage Issues

Hurmat-e-musaaharah not being established by touching one's grandmother or uncle's wife

Q: 

1. If a man touches his maternal grandmother with lust, does the marriage of his mother with his father break? 

2. If a man touches his paternal uncle’s wife (Chacha’s wife) with lust, does his paternal uncle’s marriage break? 

I am dealing with a lot of thoughts about hurmat musahara.

Masturbation

Q: Scholars who don't allow masturbation as adopting lesser of the two evils like to avoid zina when there is real fear, do these scholars consider masturbation and zina equal in sin, when only done to avoid zina. What's their stance like many Maliki scholars and Shafi?