MY NEW 19" WHEELS, finally on..lots of pics

[Perfectlap]

I would add the skirting first and then see if you are pleased with the look or if you still feel as though lowering is necessary.
The eibach springs made for the Boxster are popular but I personally have never been keen on the idea of lowering the car unless you are adding full coilovers like the Bilstein PSS9's which allow you to raise or lower the height at any time and you can also adjust the firmness of the shocks. Doing only the Eibach springs is a gamble because where ever your car sits, that's where its going to stay permanently unles you then pay to undo it. I've taken that gamble several times with other cars and sometimes its been a disaster because there are many variables like your shocks and their condition, the size and weight of your wheels, weight of your tires.
as for the center caps I guess you could probably buy a set of replica caps (if you can get them cheap) and take them to a body shop that can color match your wheels (or are they not painted? Can't tell from your pics). Tape up the crests and have the body shop paint the rest of the cap.
p.s.
How much do these 19" wheels weigh?