Ah, melding...of course. But yeah, I'll stick with Summoning Bells all the way to 100 probably. It's not that bad as long as my friends don't get tired of me. :P

And my best guess about being able to boost from 0% is that you can, but it goes into the negatives. In other words, if 90 skill meant exactly 0% chance, then you boost it from there, but if 86 skill was -6% chance (which would display as 0%), and you boosted it by 10%, you'd have a 4% chance of success. Those are all just example numbers. I forget what the actual numbers would be.