Removal of hair for one performing hajj and qurbaani

Q: I know that if a person will be performing qurbaani, then he should avoid removing his hair and nails during the first ten days of Zul Hijjah, until his qurbaani animal has been slaughtered. 

However, I was told that when performing hajj, you should remove your hair and nails before the 7th of Zul Hijjah. My questions are as follows:

1. If you are performing both qurbaani and hajj, then when should you remove your hair and nails – should you remove them before the 7th of Zul Hijjah or before the 10 days of Zul Hijjah?

2. Do you need to perform the qurbaani yourself, or can it be performed on your behalf at home by some family member (i.e. parents, siblings or children)?