Sharing the same hairbrush

Q: A family member keeps saying that he was told family members/friends, etc. should not share the same hairbrush as it creates envy and jealousy, he says a Moulana told him it's a hadith (he won't say which Moulana though). 

Now, as an Aalimah, I don't recall learning about this hadith but I could be wrong. Can you please help me out.

Sharing one's lifestyle photos on Instagram

Q: I want to build a professional Instagram profile for networking, career growth, and attracting business clients. To build this image, my pictures will naturally show my lifestyle, including how I dress and the nice places I visit. I previously avoided this out of fear of Riya (showing off) and Nazar (the evil eye). If my intention is purely professional and not to boast, is it permissible to share these lifestyle photos? How do I draw the line between presenting a good image and showing off?

Reusing a grave of a family member when there is space available in the graveyard

Q: Is it permissible to reuse a grave of a family member, burying the deceased at 4 feet deep, whereas the original deceased was buried at 6 feet deep? The remains of the first deceased (who passed away 3 years ago) would thus not be exposed. 

There is however sufficient space available in the grave yard.