two basic questions for opponents of K-12 school choice

When dealing with opponents of educational choice in K-12, I'm never able to get answers to two basic questions:

1.) How do you reconcile the supposed evil of educational vouchers with the apparent glories of the GI Bill?

2.) If public schools are under-funded, what number/range of spending per student (or classroom) would be sufficient?

Opposition to the pro-choice position in K-12 seems to be mostly a lack of policy imagination, trouble with logic and arithmetic (confusing lower total spending with higher average spending), a devotion to crony capitalism and labor market cartels, or a penchant for statism.

Christ says millstones are involved, so be careful!