2) You break for the circle with relevant Vis Ref (you don't need the RW in sight yet - that's for the final descent below Circ. Min. Alt.), but no later than the IAP Missed Approach Point (obviously) [the MAP for an ILS is the point where the Glideslope intersects the ILS DA]
ICAO Doc 8168, Section 4, Chapter 7.2.2 says
7.2.2 After initial visual contact, the basic assumption is that the runway environment should be kept in sight
while at minimum descent altitudeheight (MDA/H) for circling. The runway environment includes features such as the
runway threshold or approach lighting aids or other markings identifiable with the runway.
Personally, in reality, if I can't see the runway itself at this point, I'm going somewhere else.
Mucking around <1000' in a commercial jet without being able to see
exactly where you want to go is asking for trouble IMHO whatever the legalities.