Rayiner already addressed point 1, so I'll take a swing at 3. Most legal systems, demonstrated here by the ABA model rules of professional conduct for lawyers,

Rayiner already addressed point 1, so I'll take a swing at 3. Most legal systems, demonstrated here by the ABA model rules of professional conduct for lawyers, would not consider this a conflict of interest, unless the lawyer were arguing for both sides in the same case. See Rule 1.7. In these tribunals, government and corporate parties aren't two sides of every fight, they're arbitrary categories of parties. All good legal systems allow private parties to bring suit against the government. NAFTA Ch. 11 is an example of a very similar system working well to address legitimate disputes. See cases where a corporation's claim was rejected, and they were forced to pay attorney's fees to the country they sued in the tribunal. Not exactly the outcome predicted here.