Hi Scott,
1. Yes. And if you drag a feature from the release backlog to one of the Release columns, it sets the Release field value accordingly.
2. Yes you are correct here too. The Release/Iteration Burndown Chart works off of story points (Plan Estimate) not based on Feature sizes.
True, if not all the features for the release are broken down to stories and estimates, the chart will be missing that scope. The best practice is to do mid-range planning (Release/PI/Quarterly planning) where the teams breakdown the feature into stories, identify risks and dependencies and commit to a plan for the timebox.