I would take the approach of broadcasting the vote to several monitors. When you place a vote you get a confirmation number. That vote is then uploaded to N third parties that later verify that they all got the same votes. Then the voter could go online, type in this special ID and verification code and see that indeed his vote was counted as voted.

This doesn't mean that you couldn't or shouldn't have a paper trail as well. As long as you have a single end-point, then yes, the issues you brought up are valid.