Buying a % of a buddy at this year's WSOP - some questions

[7n7]

I've never done this, so just wanted to clarify a few things.

I'm considering buying a 1/3 of one of my friends in one of the upcoming $1500 WSOP events this summer.

1. The buy-in published includes the juice for WSOP events, correct? $1500 is the total as I don't see any other fees listed anywhere.

2. If the buy-in was something like $1500+$100, does one usually offer to pay 1/3 of the $100 as well?

3. Say he wins the thing, my cut comes from his profit not including the buy-in, correct? Does this include tip? In other words, say he wins $100k, he subtracts out the buy-in, gives me $500 back and then gives me 1/3 of the rest...before or after tip?

4. I assume it's after tax as well if he chooses to withhold at the time of award.

Thanks and my apologies for the newb-like questions!