With 07's you still need to:
1. Install and monitor aftermarket gauges (the OBDII monitoring systems are best IMO)
2. Maintain your coolant health (and install a filter). Even the Ford Gold can be OK, but most people are upgrading to ELC coolant (diesel rated). Even with coolant maintenance, some oil coolers plug (primarily with sand IMO) and must be replaced.
3. Be prepared to address high pressure oil leaks with upgraded parts (STC, dummy plugs, and standpipes)
4. Be prepared to install a BulletProofDiesel EGR cooler (doing it roactively makes sense IMO) .... or properly delete the EGR system.
5. Maintain battery and charging system health, but be prepared to send your FICM out for repair when it starts getting weak
6. Install a fuel pressure sensor and gauge, and be prepared to install a Ford upgraged fuel pressure regulator spring.
7. Fluid and filter maintenance is just as important as any other model year.
All-in-all, there are desierable changes in the 06 and 07 model year and the mods to make it reliable are a little cheaper than the other years IMO. Head studs are optional (but desireable for the best reliability and will enable some nice tuning) if the engine was well cared for (hard to verify this though).