[ChrisBennet]

Yes, you've got the idea.
Step 1: torque all head bolts to 11 ft/lbs
Step 2: turn each nut 90 degrees further

The object of tightening a fastener is to put a certain amount of tension on the fastener. The most accurate way to measure this is measure how much the fastener stretches. Obviously that isn't too practical (or necessary) for most fasteners.

In place of measuring fastener stretch, the torque to tighten the fastener is used instead. This is pretty easy to do but the downside is that the actual torque applied can vary by up to 80% due to differences in friction. The higher the torque the more effect friction has.

The torque angle method is used to torque a fastener up to a low torque/low friction effect starting point before stretching the bolt further by turning the nut X degrees.

[rant]
Torque is a very crude method for tensioning a fastener. A nice torque wrench with 2% accuracy means nothing if you are using a rusty nut and washer with no lube vs new fasteners w/30 wt oil or fasteners that aren't rusty but have been made smooth by mulitple uses. In other words, IMO people concentrate too much on the accuracy of the torque wrench when they should be more concerned about duplicating the conditions under which that torque spec is valid.
[/rant]

To answer your 2nd question, it would probably be better to remove all the head stud nuts and the retorque. However, (speaking as someone who already has reserved seating it hell) I would just remove the 4 nuts and their washers, rub the top of the washer and the bottom of the nut (the friction surfaces) on some 600 grit abrasive paper. Clean them off and then apply a little antisieze (Optimoly HT) to the bottom and threads of the nut and torque angle them in a star pattern.

-Chris