Is a Scan of my receipts enough for my accountant in order to state my expenses for tax refunds?
Or does my accountant need the total-100%-original-paper-receipt?
Are there any laws about that in USA?
For tax preparation only, it is up to the preparer to ask for receipts or not. If he does - copies are usually fine.
Keep in mind, however, that while tax preparer can rely on the information you provide, in case of the IRS audit of the tax return - you may be required to show the receipts. In this case, you have to ask your counsel (EA/CPA/Attorney helping you through the audit) what would be the form the IRS need. To the best of my knowledge, copies are fine as long as they're not altered in any way (i.e.: a copy with something photoshoped to it won't fly and the whole expense will be disallowed).
Israel will rely on your US tax return to process refunds, but they also may audit you, if the Americans don't.
Since its more than a simple tax return - I suggest you employ a EA/CPA licensed in the State where you are in the US and also in Israel (there's a list on the US embassy site with the US licensed CPA working in Israel).