Disabled pupils can have 'reasonable adjustments' to the administration of the test, given supporting evidence. Eg, for learning disabilities - extra time or breaks.
> What if the child isn't a native English speaker?
They will need to cram vocab. - as are their English speaking peers.
> What if teachers of younger students only teach to this test and ignore other important topics?
The teachers explicitly don't teach to this test, and would be sanctioned if they did such that all the other areas of the syllabus were slipping. It is up to the parents to arrange preparation one way or another.
Having said that, the school work does overlap - they start to have time limits on tests, and as always there is a strong emphasis on reading, comprehension and vocabulary. However, the particular mechanics and mindset of the 11+ are not covered.