Absolutely - this is valid document to proof your losses.
For winning amount and taxes withheld there would be issued a form W2G - http://www.irs.gov/pub/irs-pdf/fw2g.pdf
You should receive this form from the payer. The same form should be sent to the IRS as well.
yes, you may use a casino win/loss statement a valid document for proving losses reported on your federal tax return. You may present this document in case of audit.
However the win and loss amounts are reported separately on your tax return.