First off, welcome
Best place to start is with Sam's CRD Noob Guide. Run through that and let's see where things sit.
For OBD-II code reading, I'll recommend an ELM327 Bluetooth Adapter, the Android device of your choice, and the Torque Pro app. Been using this combination for about a decade and recommend it strongly. Torque also has a free version, but it's more than worth the $5 being asked for it.
General notes:
- If the glow plugs are still ceramic, replace all 4 before one breaks a tip off and damages a piston, liner, or valves.
- How did you determine that the injectors need replacement?
- Clogged EGR is very likely. Best bet is to install a delete kit and clean out the manifold.
- Turbo underboost could be a number of things. A torn airbox-to-turbo hose is a definite possibility, so inspect that first along with the air filter. OEM replacement hoses are here; silicone replacement hoses are here. Silicone is strongly recommended; if you go through the noob guide and find out what the CCV system does to the rubber hoses, you'll know why.
- As for the rest, you could have a removed CEL bulb; I've seen sellers pull that sort of thing in the past. Read the noob guide, chase up the items above, get a cheap-but-serviceable code reader, and let us know where you are after that.
BTW: you might want to post in the CRD Forum with questions like these - they'll tend to be seen faster
