You can make any equip you have access to (that shows up in the window), at least with Jeweler.
It failed unfortunately (but still got 63 exp for the profession)
The benefits of raising your profession level is probably an increased success rate, which may also increase as your character level approaches the level of the equip. With Level 1 Jewler, I had 21% success rate for that ring, which has a Recommended Level of 6, and at Level 2, I would have a 29% chance of success, according to the skill UI at least.
Everything over 100 appears to need the recipe thingy.
Oh, and there are new monster crystals as well. My dit has both the old Basic Monster Crystal 1 and the new Basic Monster Crystal 1, so they're completely new items that don't replace the old monster crystals, so the ones we have now will be completely useless.