You don't need a DSG tune but they're nice. I'm not sure what tools Scheids has but they can probably do them. On a 2005-2006 its only needed after Stage 2, 2009+ its needed for Stage 1 or more.
Left foot braking: if you use both pedals, without the mod it cuts fuel, its just some coding in the ecu to allow this. Its primarily for those who track their car.
Dynamic EGR is one of my favorite features living in the tundra, at 0F it takes a good amount of time for the engine to warm up without an EGR.
Dynamic idle is ok, I don't like it with a heavy or grabby clutch but otherwise its nice.
Yes, Malone can do 2012-2014 Passats.
I have tried a Stage 2 tune on a BRM and BEW cars but their tiny turbos just can't handle it, that is why the Stage 1.5 tune is there. Every once in a while you'll find a car that won't mind Stage 2 but its not common. If someone had boost and EGT gauges and knew what they were doing and willing to take the risk, I'd give them a Stage 2 tune.