Eliminating lifetime tenure for Federal judges is problematic, each party has made its own uses of this. The main purpose for it is to ensure judges can decide cases on the law alone, without worrying about how it will affect their fortunes in later life when their term expires, and the fact that 'being held accountable' is not the same thing as 'being held
justly accountable' but often boils down to 'It's payback time for you doing what I didn't like, you SOB.' I would rather see a mandatory retirement age than a definite term on these officials.
2. Congress should have the power to override Supreme Court decisions with a two-thirds vote.
Sucky idea, especially given number 4. Basically makes interpretation of the Constitution a political issue rather than a legal one, which would certainly lead to some very bad unintended consequences if one party ever got a solid upper hand in Congress, as the Dems did for a very substantial part of the 20th Centruy. And anyway, Congress already has this power in effect, with the Amendment power, but there are additional checks and balances on them that prevent getting carried away like they could if it were entirely in their hands.
3. Scrap the federal income tax by repealing the Sixteenth Amendment.
OK with me, has to be replaced by some other revenue-generator though, whether it's a flat tax or VAT or something else entirely. I'd be happy with just changing the tax code to a flatter, broader, and simpler system, even if the Sixteenth stayed.
4. End the direct election of senators by repealing the Seventeenth Amendment.
Not necessarily a good idea. Both the pre-Amendment method and direct election have their pluses and minuses, direct election for instance is a true popular, ungerrymandered statewide vote so has some sound Populist principles. I'd rather see Constitutional term limits on both houses of Congress, such as three terms for a Senator and six for a Representative, which gives both a full career but doesn't allow for the them to become fossilized sphincters.
5. Require the federal government to balance its budget every year.
Good with that one, it would need a phase-in period to avoid fiscal chaos though.
6. The federal Constitution should define marriage as between one man and one woman in all 50 states.
Cool with me. If a State wants to have a 'Civil union' that is essentially a householding contract under their law, I don't have a problem with that, but it's a travesty of the language and a debasement of 10,000 years of human civilization to call it a "marriage."
7. Abortion should be made illegal throughout the country.
Probably not gonna happen, at least as a 100% ban.