Thanks for flying my favorite airline.
That first picture looks like gate D3 or D4 at SEA.
The strake, or vortex control device (VCD) in Boeing speak has always been on the inboard side of the engine.
The bump that looks like a ski jump is the krueger door seal fairing that creates a seal against the k-flap when extended. Just inboard of the fairing is the krueger flap deflector(the short thick strake). The purpose of this is to force the krueger flap door to hinge aft when the thrust reverser translates aft.
Don't see any obvious visual difference between that winglet and any other winglet on the Alaska Airlines NG's. There is a similar version that uses a single lense for the strobe/position lights.
The strakes (VCD) are a big enough deal that they cannot be CDL'd, so they must be present. Yes the fan cowls can be interchanged between positions. The strake has to be added or removed depending on position. For example, you could remove the no.1 outboard fan cowl, attach a strake and install it at the no.2 inboard position.