-Grand prize winner will be paid in BTC through their original sender's address.
-If it becomes necessary to prove winning pay out we will publicly announce the winner's bitcoin address. If this concerns you, please purchase your lottery tickets using a different address.
I don't get that part. Are you saying you are going to have a different address they can secretly send to? That will make jackpot amounts impossible to verify.
How are you giving out the "tickets" and picking the winner?
Making it so you can just "pick" a random number makes it impossible to know if you are just getting a "random" number that will allow one of your own tickets to win every time!