You should probably save your money and not buy a chip (for either the engine or transmission). Next you should find someone local to you who has a VAG COM and have them set your transmission into sport mode, you'll need to search around the forums here to find out some background info on this setting. Not sure about the springs but it sounds like Traubenburg has already answered that question.
Welcome to Passatworld, fattybangger!
I had good results from the GIAC chip, but you are only talking +5 to 7 hp/ tq gain at the wheels for 300.00. It really does its best around 3,000 to 4,500 rpms in 3rd and 4th, but also run 93 octane with it (minimum 91 octane).
Do look into getting the Tiptronic locked into sports mode via VAG-COM.
Depending on the particulars of your car (milage/ maintenance done) the 300.00 for the chip might better be spent on maintenance (same as money you are thinking of spending on springs, etc.).
Yeah, definitely get the supercharger if you want to do one thing to your engine that will actually make a difference. The 1.8t benefits from being chipped because the factory software limits the output of the engine to start with. That's not the case with the V6 -- if you want more power, first you have to add something that will pack more air into the cylinders.
Of course, the supercharger costs as much as all of the possible upgrades for the 1.8t combined, so if you're going to do that, you'll need to save up for a while.
Listen to the people that have actually chipped a V6, or have one and didn't.
I had one, chipped it (plus other stuff) and was happy.
I traded it in on a W8, which I also chipped, and am even more happy.