Ran the tap through and there was no swarf when it came out, cleaned, de greased and blown out with air. They may have weakened and snapped though as you say.
Better not be the bloody head gasket!
Sequence?
Just kidding, ten bolt, centre working outwards at diagonals. Same as RAVE and the instructions that came with the head gasket.
Had a 7/16th" UNC tap handy then, that's good. Always pays to run a tap down then blow out any oil or debris. Bolts to be angle tightened should be lightly lubricated as should below bolt washer and bolt head. Light lithium grease for that application.