1. There's nothing preventing the formation of more political parties - it's just that they garner little support. Just look at the Libertarian and Green parties.
2. However, the more parties with elected officials the more likely partisan politics will be a greater problem. In other words, the more disagreements in Congress and the more gridlock we will get.
3. Polls are open from 7am to 7pm where I live. No need for another national holiday.