1. For a 44-point stat, it's 11 of each level of materia. For a 31-point stat, it's 7-8-8-8.

2. The higher the item level, the better the chances of getting a IV. But higher item levels are also more expensive, and limited on where you can SB them (anything over i55, you pretty much have to choose from a selection of instances). Personally, I've just been sticking with i49 stuff, since it can be bound pretty quickly in the open world.