Hi,
1) 0.2 delta g buffet margin = 1.2 g margin. Slightly different ways of expressing the same margin.
2) There are 2 graphs shown - @ 0.78M and @ Long Range Cruise.
at 0.78 M you'll be limited to rate of climb 300 feet per min to get to Max FL.
At LRC you'll be limited by your buffet margin.