Caster Level Buffs:
Since Dispel Magic is a caster level check, there are a lot of easy ways to increase your modifier. There are a number of traits that grant a +1 trait bonus to your caster level for certain spells, such as Gifted Adept, Lore Seeker or the more general Strength of the Land. Certain feats can also help, such as the more resonant form of Allied Spellcaster.
Caster level doesn't actually have much to do with the ability to craft magic items. In Pathfinder, you can ignore any requirement except for the creation feat by adding 5 to the DC to make the item. That can still hurt, but there are enough ways to boost your spellcraft skill (such as the Crafter's Fortune spell, the Natural Divination revelation, and the Skill Focus feat) that a sixth level character can craft most items if necessary. Since Pathfinder E6 doesn't appear to have a centralized rule set (I was only able to find the original version for 3.x in 20 minutes of Google searches), your DM may have closed that opening, but it can't hurt to ask. The DC for the Orange Prism Ioun Stone will be 22.
The Laser Cannon Flyswatter:
The best way to get rid of buffs is not dispel magic, but Anti-Magic Field. Some of the PFE6 rulesets I found had feats you could buy to replicate more powerful spell effects. As a 6th level spell, AMF might be on the outside of acceptable, but its equalizing effect is actually well-suited to the variant. Again, ask your DM.