1. No experience or empirical evidence on .us domains yet... I'd avoid at the moment as it's an unknown.
2. Definitely NOT!
3. Prefixed and suffixed 'phrase-matched' EMDs are the next best choice to an EMD. Go with a suffix first, as a prefix pushes the keywords further from the front. A short suffix like 'pro' or 'info' is usually the best. Check and see if there are some worthwhile long-tails that contain a small prefix/suffix (like 'buy.....') which could add useful juice later.
Be careful not to over-optimise the content, anchors and titles on EMDs now. Post-Panda, this is more important than ever.