I find that the P-tex candle is most convenient because it goes fast and you can make the repair anywhere, but the material is softer. A P-tex gun (looks like a hot glue gun) is the best since the molten P-tex is easy to control and the material is hard, but you need a power source. A narrow P-tex iron and P-tex tape does the job like the gun, but is trickier to use. I have never tried the powder, and can only assume that a larger area will get the material, and not just the damaged area.
So, to the wax absorbsion issue. Wax is not absorbed into the base as such. It is an analogy used by industry people. There are no tear shaped pores which draw wax in and release wax as friction creates heat. If you look at a new pair of skis, you will see structure line from stone grinding. Magnifiy a lot, and you will see that the base is quite cratered and hairy. The more you wax, scrape, brush and ski, the hairs are eventually shaved off. This leaves the craters on and between the ridges of the structure. When you wax and then scrape, the craters and structure valleys are filled. Brushing with a brass or nylon brush removes the wax from the structure, but the craters are still filled. This results in a smooth base. There will still be a certain amount of surface wax too. Friction of skiing removes the thin layer of surface wax first, and then the craters get emptied.
When you make a P-tex repair (powder, candle, tape or gun), you get rid of the structure where-ever the new P-tex bonds. The new material does not have any structure, and is much smoother than base. Becasue of this, there is no place other than the surface for the wax to fill. You need to get some fine emery paper or wet & dry sanding paper to re-create the original base structure in the repair area. The structure is to prevent suction. Put a drop of water onto a pane of glass and then put another glass pane on. Very difficult to move.
I hope this clarifies things a little.