Proper ARIA metatags for responsive table - twitter-bootstrap-3

Question

Im making responsive table and I want it be fully accessible for every people. But in this case i'm not sure where i should use rowheader and where to use columheader.
Here is my code (ofcourse it is just example, there is not actual data):
<div role="grid">
<div class="row" role="row">
<div class="hidden-xs col-sm-offset-4 col-sm-3 " role="columnheader">
<img class="img-responsive" style="width:200px;" src="http://blogmedia.whoishostingthis.com/wp-content/uploads/2013/04/free-hosting.jpg" alt="Vendor 1">
</div>
<div class="hidden-xs col-sm-offset-1 col-sm-3 " role="columnheader">
<img class="img-responsive" style="width:200px;" src="http://jennmoney.biz/assets/free.gif" alt="Vendor 2">
</div>
</div>
<hr class="line">
<div class="raty-table" role="row">
<span class="col-xs-12 col-sm-4" role="rowheader">
Title 1
</span>
<span class="visible-xs-block col-xs-4" role="rowheader">
Vendor 1
</span>
<span class="col-xs-8 col-sm-4" role="gridcell">
Content
</span>
<span class="visible-xs-block col-xs-4" role="rowheader">
Vendor 2
</span>
<span class="col-xs-8 col-sm-4" role="gridcell">
Content
</span>
</div>
</div>
Here is a fiddle:
For vendors should I use rowheader or columnheader? And how I should tag "How long can I sing?" Once it is rowheader and on different screen size it can be columnheader.
I see, it is hard to undestand what I mean, so I made two mocks, but thanks to StackOverflow I can't post it, becouse I have to low reputation...
I must post it as a link: http://postimg.org/gallery/j2elhzmc/ - first picture shows how it looks on desktop, second how it looks at smartphone (if you have the same order as me).

Answer 1

Your grid must be defined as non editable
A grid is considered editable unless otherwise specified. To make a grid read-only, set the aria-readonly attribute of the grid to true.
You should explicitly indicate relationships
If relevant headers cannot be determined from the DOM structure, authors SHOULD explicitly indicate which header cells are relevant to the cell by referencing elements with role rowheader or columnheader using the aria-describedby attribute.
Note that you might reference a "display:none" element in the aria-describedby attribute. I will say that the more semantic choice will then be to set aria-hidden attribute on your rowheader elements.
TL;DR:
Set aria-readonly=true on the grid
Set aria-describedby attribute on your "gridcell" cells referencing each one of your "not always visible" columnheader
Remove role="rowheader" and set aria-hidden="true"

Answer 2

Sorry if I'm missing something obvious but columnheader should be used at the top of each column. (You could have a columnheader in the middle of the table, but that's not typical, although I could see it used as a repeating header if it split across pages.)
A rowheader is usually the first cell in the table for that row. You can have multiple rowheaders but it's not common unless you're showing a multi-dimensional table (eg, a sales report that has a year header for all rows, then quarter headers for every three months, then month headers).
You start getting unreliable results (from screen readers) if you have row headers spread across several non-contiguous cells.
I'm assuming you don't want to use <table> and <th scope='row|col'>