A basic OPS - xsl question from the tutorial

I have been reading the tutorial in an effort to learn both OPS and some more about XML technologies.

I had been very frustrated by my inability to implement the hello-world tutorial sequence successfully on my OPS installation.  I finally realized that the tutorial was written prior to the incompatible changes introduced in 3.0.

The gotcha for me was that all XSL selects needs to refer to doc('input:instance') in order to actually access the model that the xform elements on the same page are using.

I am sure that there is a good reason for why this behavior change was implemented, therefore, my questions are:

1 - Why was this done?

2 - Is there a way to set the "default" context of an xsl document to the input:instance nodeset so that I don't have to use doc('input:instance') for every value I wish to access.  This feels very awkward.

My impression is that in order to access elements via XSL I will always have to have  a document function call as it seems that the default nodeset will always be an empty nodeset (per the 3.0 change guide).

I am sure I am missing something.

Thank you in advance,

bex