Good questions for sure, not goofy at all.
Angle tightening can be used on any screw thread fastener, especially when you don't have access to both ends of the bolt. It's way more accurate than torque, which only infers tightness. Even better is expansion, tightening to a specified stretch. ARP rod bolts are best tightening that way according to them.
Angle tightening produces a more accurate stretch in the bolt. The initial torque value is just to take up the slack. Then angle tightening takes over. The pitch of the thread is a known factor - really accurate.
On a stress-strain graph yield is the point where the line begins to flatten. Yield doesn't mean plastic deformation but it's close. So some fasteners are permanently deformed, and the bolts are replaced every time. Volvo doesn't tighten bolts into that region. The reason for bolts tightened into the yield region is that a change in strain doesn't make much of a change in stress. In the engine that means if the head gasket squishes a bit the clamping load of the bolt remains the same or nearly the same. If the bolts are really stiff they are not as "springy" and any change in the gasket (gets thinner) would reduce the clamping load a lot. So skinny bolts that yield are more common now.
It's good you decided to install a new head gasket - it all adds to reliability.