Question 1:
Yes. I usually do 30% at date of booking and 70% day before the event.
Question 2:
This hugely differs 🙂
Tiesto will ask you for 300,000 per hour plus expenses.
I will prolly ask 200 bucks per hour plus expenses.
A no-name will prolly ask less.
Question 3:
Usually ticket sales can be handled any way you like, but usually a ticket broker will boost your sales, as they also market their tickets on their websites etc. So totally depends on the deal you get and many people will want to buy tickets online.