Thomas, you've confusing process with product. While it's true that the chemical process of Pt/Pd printing works best under somewhat acidic conditions, when finished, you want the paper to end up in a neutral to slightly alkaline state for longevity. The final image is comprised of tiny particles of Pd and/or Pt which are of course very non-reactive and stable ("noble" metals). This image will last as long as the support upon which it's printed. So, a typical work flow might include an acid pre-treatment of the paper to remove any buffering compounds (oxalic acid is my preference). You also want to keep your potassium oxalate developer in an acidic state (pH 5 to 6 is good) which is accomplished by adding small amounts of oxalic acid as necessary. For most papers, post-development clearing works best by placing the print first in an acidic solution such as citric acid, then two successive baths of regular working strength Hypclear or Permawash, each for roughly 5 minutes. A final 15 minute wash should be sufficient. You should not rinse the print with tap water between the development and clearing steps unless you are certain your tap water is not alkaline. An alkaline rinse immediately following development can make subsequent clearing very difficult. Stuart Melvin and Clay Harmon both have experienced this effect. My water comes out of the tap at about pH 6.5. I believe Clay also found longer development times helped him with clearing issues. I usually develop for about a minute (developing longer has no real effect on the look of the image).

I use Rising Warm White acid-free matboard and corner mount my prints. I often cut the mat right up to the image, but sometimes not.