Congrats, you made a great decision. Brand loyalties are so subjective, but based on my research and limited experiences, Walther is a cut above Kahr in all respects (maybe not customer service? Now that Walther is separating from S&W, their CS will remain to be seen). So if it really came down to how many mags were in the box, I would definitely have taken the Walther over the Kahr on reputation alone. I think you'll be happy with your new gun!
For holsters, Crossbreed, High Noon, or Raven Concealment will all make you a great holster for your PPS, depending on what style you prefer.