I've tried to do my homework on this topic and educate myself, but still have a few lingering questions that i'd like answered before I decide to move forward one way or another.

First things first, I've got a CEL right now for a vac leak. I've got at least one bad check valve and some bad hoses that need addressing. I considered doing the vac system delete following the Audizine DIY when I had to replace a coolant flange, but fought my way through it. Now that I've actually got a vacuum leak i'm at a crossroads and am looking for insight from fellow A4 folks.

Couple things i'd like to know if I proceed with the removal:

1. When the system is removed, what codes appear? How can these be removed? Tuner? (If it requires a tune, how expensive, and is it worthwhile as my car isn't even chipped at the moment) I've heard you can use resistors as well? Will I still be able to pass an OBD emissions test?
2. After the system is removed, how does it affect performance and fuel economy??
3. I think if I were to go down this road, I'd install a catch can system. Any recommendations. Recirculating system or vented?

Any advice is appreciated.