Help: on 7 mukhi rudraksha

[whatsindname]

Hi

i have few doubts regarding rudraksha, please help me out:

1) some says 7 mukhi rudraksha can be worn around neck and some says it should be kept in locker and should not be worn. which one is true?

2) mercury is enemy planet in my horoscope, can i wear 4 mukhi rudraksh?

3) since my ruling planet is jupiter, should i wear 5 mukhi as well?

4) most importantly, some says it should be worn in black thread, and some says red only and few says u can use any..

please guide me.

thanks