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.
1. There are many state and federal laws which prevent these political parties from being on the ballots and/or debates. So yes, there is plenty of political power against the proliferation of these parties. Although the winner takes all voting system also perpetuates a binary division of political beliefs.
2. Not necessarily. Coalitions are a notable feature of multiparty politics. More disagreements will be resolved because say Republicans and Libertarians can overcome Democrats on an issue they both agree on but Democrats disagree with, and likewise Democrats and Libertarians vs. Republicans, and likewise Republicans and Democrats vs. Libertarians.