Bootstrap fluid layout - fixed width of sidebar

Answer 1

I think this is what you need: http://jsfiddle.net/U8HGz/1/

Answer 2

I think you are looking something like this:

<div class="sidebar span4">
    this is my fixed sidebar
</div>
<div class="main">
    <div class="container-fluid">
        <div class="row-fluid">
            <div class="span2">this is fluid</div>
            <div class="span3 offset1">yeah!</div>
            <div class="span6">Awesome!</div>
        </div>
        <div class="row-fluid">
            <div class="span6">1 half</div>
            <div class="span6">2 half</div>
        </div>
    </div>
</div>

here´s a fiddle for your convenience: http://jsfiddle.net/TT8uV/2/

As as general note:

You don´t need to use bootstrap as your 'main container', so you can place your sidebar side-by-side with a grid system (like bootstrap fluid and responsive). This way you have A LOT of control of the sidebar, without affecting the actual content.

Hope it works for you.