Rerolling Charms

[dectgap]

OK why is it that shimmering on a small charm can only appear (on 3 perfects plus magic re-roll) if the monster dropping it is level 47, even tho the affix is a level 33 affix? And yet for a grand charm with +1 skills, I can re-roll it with the monster dropping it is level 50, even tho the affix level is also 50? Whats up with that?

The alvl of an item depends on the qlvl, aswell as the ilvl. Have a look at the alvl calculation (can be found under Explanation).

Also, that page (linked above) that does the affix calculation shows that a GC can only have 12% resist all, but I'm sure I've seen a 14% resist all GC.

In 1.08, Grand Charms could get up to 15% resist all (from the Shimmering prefix), so the charm you have seen must have dropped pre 1.09.