Hello guys,
I have some questions regarding to paying tax and gambling in the U.S,
appreciate in advance your help on this subject.

First, let my clarify that i am not consider a professional gambler according to U.S tax law , because i currently visit the U.S for only three month,
and the last time i have been here was 7 years ago, so in between a 3 years period, i have only visited U.S one time, , ( knowing by reading a U.S gambling tax book, i hope i am right on this one ).

My questions are:

1. If i am leaving the U.S with more money, do i have to pay 30% tax, for example lets say i have entered and declared for 20,000$ and now i am leaving with
30,000$ will they reduce 30% percent from the 10,000$ i have won in the casino ?

2. What proof do i have to bring to the customs officer , so he will actually believe that the 10,000$ win is actually a wining money from the casino ?
(i thought about taking a pic of me next to the store, as well as show him a detailed excel file of my wining and losses, perhaps even considering recording the
conversation in the store cashier using my spy iPhone app so the date the location and the amount of money will be recorded as well).

3. If i considering sending part of my money using wire transfer to my bank out of U.S is there a different between my marked bills that i have declared in the
customs and wining money from the casino, do they ask questions if they find out this is not the money i have declared , what reason do i have to give them
for transferring the money, in this case i want to make multiple transaction each for 4000$ so the total transaction amount is more then 10,000$.

Let me mention also that i am only playing table games,
so my winning from blackjack is totally differ from a guy who is playing slot in a matter of paying 30% tax, but how can i prove i am only playing blackjack ?

Thanks again for the help.
I hope some of the professional will know the answer to my questions.