I did not choose the term. The term was originally developed by William Dembski and Robert Marks in their analysis of evolutionary algorithms. Active information is the amount of information an algorithm has about the space it is searching.
Quoting from the paper:
The point of this is that it would have to be tested to know. The point of doing this is to establish a way of measuring it. It certainly would be interesting to find out.
Any sufficiently blindly chosen set of mutations should be workable, but I think the optimal way to do so would be a binomially distributed set of mutations at the per-base pair mutation rate of the organism.
It depends on what you mean. If the per-organism mutation rate increased, but the actual mutations per organism remained the same, that would not be considered active information on this calculation (we are basically only considering organisms that do have mutations). If you mean that the per-base-pair mutation rate changed, then whether or not it was active information would have to be determined experimentally.
No, but I don’t think it is relevant to the measurement. Nothing in the proposed experiment assumes a given amount of junk DNA.
Again, the point of this is to minimize assumptions - to find a measurement which is largely independent of what we think about it. If you knew unquestionably that junk DNA was junk, and you also knew unquestionably that the mutations here were haphazard, then sure. However, I do not think we know these things. Even many things which were supposedly unequivocally junk DNA have come into question. For instance, there are organisms for which pseudogenes play a large functional role, sometimes simply as repositories of alternate configurations of genes.