Ok, this is a lot to reply to, but...
@Othelos: All the way back up to your idea of the legislature, with your idea, do you mean the legislature should be unicameral, with an election system that is somewhat in between proportional and static representation?
Second, I agree with you about the IRG; I don't think any of the regions plan for it to make us so unified we're like the states. Each of the regions will keep their governments, so most of the administration will fall with the individual regions, but the IRG will be there to serve as the central power to keep the IU's working together. I see it as having just enough power to allow the IU's to act as one political unit, keep the regions working in unity, and greatly increase the influence of all four regions. I do agree with Zera that the regions shouldn't be able to repeal IRG legislation; that should be left only to other interregional administrations.
@Xin Prussia: I can agree to an appointment system for the VP. Should the president appoint him/her after being elected, or should we use a running mate?
I also agree that the minister of finance is without use. As money is entirely roleplay, that position wouldn't have any role in the government.
@Zera: I suggest we make the VP the vote counter for the Senate. The Speaker should be separate, as that position is going to take a lot of activity to keep so many legislators organized.