Personally, I don't do selfings and I don't usually buy them either. I bet an outcross will show you a better germination rate.I've selfed it a couple of times, and germination has been poor. There are a few seedlings this most recent time. I'll save some pollen and try putting it into a different roebelenii when it blooms (maybe this year).
Hard to say, and lots of variables. I think there's more problems with different techniques/agar formulas and species differences before inbreeding depression issues set in. Even outcrosses of randsii, venustum, and parishii are notorious for poor germination. I had (at Troy's) selfings of lowii, philippinense, and supardii that have yielded very good results.Personally, I don't do selfings and I don't usually buy them either. I bet an outcross will show you a better germination rate.