[1]
For an overview of the major theories and their challenges, see Jacob (2010, section 9) and the references therein.
[2]
One possibility here has been explored recently by Karl Friston using the concept of a Markov blanket, which produces a kind of partition between information states.  As I read Friston, he advocates a pluralism about Markov blankets.  On this view, there is not one boundary between mind and world, but instead there are a number of salient boundaries within, and perhaps around, living organisms. Friston writes that “ . . . a system can have a multitude of partitions and Markov blankets . . . the Markov blanket of an animal encloses the Markov blankets of its organs, which enclose Markov blankets of cells, which enclose Markov blankets of nuclei . . .” (2013, p. 10).
[3]
For a theoretical treatment of the functional significance of this convergence, see Metzinger & Gallese (2003).
[4]
When first developing the framework, he used the more general term “intention” because he was dealing with linguistic meaning, not perception.  When applying the framework to perception one can be more precise about the nature of the empty perceptual intentions: they are anticipatory.  In his later work, his Analyses of Passive Synthesis from the 1920s, Husserl ties in perceptual intentions with his work on time consciousness (1969) and refers to them as protentions (Protentionen; Husserl 1966, p. 7).  In the same work, he refers to perceptual protentions as anticipations (Erwartungen, 1966, p. 13, and antizipiert, 1966, p. 7).  See Madary (2012a) for a discussion of how Husserl's framework can be situated relative to contemporary philosophy of perception.  Also see Bernet et al. (1993, p. 128) and Hopp (2011).
[5]
For impressive empirical work on this theme, see Freeman & Simoncelli (2011).