You'll always be missing something, its just part of the hobby. That said..

• You might not get much use from the GPS without an OSD module. I haven't set that up yet myself, but don't really get how its useful without seeing any output from it. You might try building without that first, then upgrade, its complicated enough without it (especially if your new).
• You'll want a separate (smaller) battery or LC Filter for your camera/transmitter circuit or your going to have terrible FPV video. -- If you go the LC Filter route, take note that your camera input voltage range is 6.5-12V and your 4S battery is supplying more than that, you'll also need a 12V step down. Your VTx will probably have the same issue, but you can put them both behind the step-down.
• Buy more props. Double what you have, they go fast.
• I'd buy another voltage monitor without the beeper, it gets real annoying when inside just testing batteries.
• Toss in some mushroom antennas, they tend to work better.
• That charger has alot of reviews saying its a fake knockoff. Up to you on that.
• Add some Lipo Storage bags for charging. You don't want one of those exploding in your house.
• Your charger might not come with a JST plug, I had to make mine even with a higher priced charger.
• If you're 3D printing a frame, you're going to need hardware (screws, bolts and such). Surprisingly Home Depot in my area does not carry hardware that small, but the electronics store in town did.
• If you don't have these things, add them: RC Breakout cable, Heatshrink, zip-ties, double-sided tape or velcro (I like dual-lock), solder, soldering iron, Micro-USB for the Naze.

For reference, I only built 1 quad two months ago, so my experience level is low.