Google Sheets – View and Edit Data in a Form

Google Query Language will return a JSON string. To get the cell value and format as you see in the spreadsheet, instead of /gviz/tq?tq= and the query string, use /pubhtml?gid= and the "right" parameters.

The easiest way is to get the URL resulted of publishing the spreadsheet to the web. Then...

Add range=A1 to the URL of the published spreadsheet, where A1 is the cell that you want to display.

I.E. for https://docs.google.com/spreadsheets/d/1NIIqpRSYCXT0OlvDgXa0g4GVxmrnvQOSn_L-HcgPqVA/pubhtml?gid=0&single=true

to display only the cell B13, the resulting URL is:
https://docs.google.com/spreadsheets/d/1NIIqpRSYCXT0OlvDgXa0g4GVxmrnvQOSn_L-HcgPqVA/pubhtml?gid=0&single=true&range=B13

to remove the header, add chrome=false:

https://docs.google.com/spreadsheets/d/1NIIqpRSYCXT0OlvDgXa0g4GVxmrnvQOSn_L-HcgPqVA/pubhtml?gid=0&single=true&range=B13&chrome=false

Note:
Use ? before the first parameter.
Use & when adding the second and subsequent parameters.

References
Publish a document, spreadsheet, presentation, or drawing - Docs editors Help
Cómo publicar en Web un rango - Ejemplos para los foros (How to publish a range in the Web - Examples for forums, self citation)

One approach is to add a status column next to the data input: for example, in L10 it would be

=if(iserror(match(H10, H11:H, 0)), "current", "obsolete")

which returns "current" if no entry below the present row has the same email. Then your query can filter out the obsolete results.

The above does not work with arrayformula. I don't think there is an arrayformula-compatible approach, because the number of comparisons is quadratic in the size of array. Here is a script solution that auto-expands: put status(H10:H) in a new column, with the following function in a script.

function status(arr) {
  flat = arr.reduce(function(a, b) { return a.concat(b); });
  var output = [];
  for (var i=0; i<flat.length; i++) {
    if (flat[i] === '') {
      output.push(['']);
    }
    else if (flat.slice(i+1).indexOf(flat[i]) === -1) {
      output.push(['current']);
    }
    else {
      output.push(['obsolete']);
    }
  }
  return output;
} 

The approach I took in this answer also works reasonably well here: use unique to get unique users (identified by emails), then filter rows by email, and use vlookup to pick the data just from the last row. The result will be a neat summary table that has only the latest data.

Using your example, I build such a table starting from the cell A20. In A20, I enter

=unique(H10:H)

obtaining the list of emails. Then in B20 I enter

=vlookup(999999, filter($G$10:$K, $H$10:$H=$A20), column()+1)

and extend this formula to the range B20:D. This is the result:

+-----------------------------+-----------------+--------+-----------------+
| peter.goedtkindt@school.edu | SpecializationB | 2016.2 | changed my mind |
| student1@school.edu         | SpecializationB | 2016.1 |                 |
| studnent2@school.edu        | SpecializationC | 2016.1 |                 |
+-----------------------------+-----------------+--------+-----------------+

(I don't know if you needed comments, but I included them anyway.) Using column()+1 as the last parameter of vlookup allows the formula to pick the relevant column, after vlookup with absurdly large search key 999999 zooms in on the last entry.