I know these are in a legal grey area, so answering what you believe would be the "most likely scenario" would be greatly appreciated.

1) Is Bitcoin-Denominated Debt Enforceable?
In other words, say I lend someone X BTC (unsecured), and get them to sign a promissory note for the X BTC loan, etc... etc... Now, assume they didn't pay me back. Could I theoretically pursue them for this debt, and potentially take them to court? If so, would I receive only the USD value of BTC lent, or is there a way of writing a contract such that they would be obligated to provide me with the actual X BTC, no matter how much it is worth in USD terms, now?

2) Do normal usury laws apply to BTC?
Self explanatory.

3) Do I have to report income tax on interest earned from BTC loans?
Or do I only have to pay such tax when/if I exchange that newly earned BTC into USD?