Catch can:
Essentially adding a catch can eliminates the Pcv valve, which is important because when you are boosting the PCV valve closes and the crankcase cannot ventilate, at best causing mild oil leaks and at worst causing massive blown seals and oil leakage everywhere like me.
Then, get a blow off valve, I really like HKS's sequential BOVs (the Super Sequential Blow-off Valve, the Racing valve and the gangsta old-school Sequential Blow-off Valve). Re-circ it for optimal performance but leave it atmospheric for best sound. After this I would contact Rocketman and buy one of his ECUs, disconnect the overboost sensor, crank the boost to 16 psi, buy a downpipe back exhaust, add a front mount intercooler and change the clutch (clutchnet has great price and products even if their customer service sucks) if you get bored with that and haven't crashed into anything come back and we'll tell you what to buy next.
Note that this is completely ignoring suspension and brakes, if you do all of this on OEM brakes and suspension with all-season tires you will probably die. I'm at stock boost with the stock turbo on summer tires (during the summer) and I almost die on a semi-regularly basis.
If you keep the stock turbo I don't think that an AFR gauge is necessary as long as you don't use your boost controller until you have a new ecu(Gus, you killed yours cranking boost on the stcok ecu, didn't you?) but if you really do want one look at PLX, Innovate, tech edge, zeitronix, Horiba or Motec, listed in a rough order from cheapest to most expensive. I'm getting a PLX and my dad runs Tech Edge. PLX should be fine for your app, just get one with a gauge or display.
Also, finish your tune-up before adding any more parts, this is fairly vital to not blowing up. cap, rotor, fuel filter and an oil change. For plug wires, good Motorcraft wires will probably be good enough for your app, I would recommend not using Autozone specials. If you're a baller go for 10mm magnacores, they're as bad-ass as plug wires can be.