In regards to crossing restrictions:
http://www.faa.gov/about/office_org/...sselles_Jr.pdf
Quote from that letter:
Based on your question above, we assume that the assigned cruising altitude was the last
clearance received prior to communication loss. Under that assumption, if the cruising
altitude is the highest of the above three referenced altitudes, then that is the altitude the
pilot should use for that route segment, notwithstanding that the intended arrival may
contain mandatory crossing restrictions.