Mold on the pipe is a problem you probably can't fix. "Cleaning" it by removing the residue will not kill the mold, and it will reappear if/when the environmental conditions are right. Generally, that means a warm, moist ambient with poor air circulation. A picture frame is often warm inside, as light radiates through the glass, and there's no free circulation of air. All you need to make it grow wildly is some humidity. I suggest you contact a conservator who specializes in objects. Paul Storch comes to mind immediately.
If the mold developed inside the existing frame, then the mold has probably permeated every hygroscopic thing in it. You should start over again with all new materials.
Mounting is another issue. If the pipe has any monetary or sentimental value -- and my guess is that it does, otherwise the customer wouldn't want it framed. For preservation purposes, the mounts should be non-invasive and removable at any future time. In other words, don't change the pipe in any way. Clear film straps would be my first choice. No glues of any kind.
