Stage 4 costs paid from cash flow from remnant ore.. $15 million...

Stage 4 costs paid from cash flow from remnant ore.. $15 million needed.

That is the expected position

They can start mining stage 4 before building the sea wall.

That is correct. PLV calls it the scavenger pit option. This involves a cut back and relocating stage 4 ramp and removal of a lot of waste. Mining at depth is limited until the sea wall is constructed.

Stage 4 seawall is not slated to start until 2Q 2013

That might be the case NOW but:
The seawall construction was expected to commence JANUARY 2013 as per this announcement ,

http://www.asx.com.au/asx/statistics/announcements.do?by=asxCode&asxCode=plv&timeframe=Y&year=2012

Stage 4 ore from surface will be available to blend with ore from other sources while the seawall is being constructed, which is scheduled to commence in January.

If it is now Q2 2013 then we have had a delay.

Stage 4 mining (should have) started in February.

According to Table 1 on page 6 of the Orelogy report, Stage 4 mining( scavenger) should have started in October 2012, immediately upon transfer to PLV, not February 2013.
Section 3.9 of the report reads: The Stage 4 Scavenger Pit option is the portion of Stage 4 as shown in Figure 8 that can be mined without the requirement of building the new seawall and involves a cut back and relocating Stage 4 ramp. In reality this is phase 1 of the Stage 4 mine plan ....... is scheduled from October 2012 ..... utilising conventional mining methods.