1) If youre doing it right than you will deck the heads. Ford specs for flatness are rediculously inaccurate. Get them checked.
2) The root to the EGR and headgaskets problems are due to the Ford's coolant. It contains silicates which fall out of suspension from high EGT's and form into a good type substance. This good clogs up the factory oil cooler. Since the EGR cooler is down stream from the oil cooler, when the cooland cant pass through the oil cooler to cool the oil, than it wont make it through to the EGR cooler to cool exhaust gasses. Then EGR cooler then over heats and ruptures dumping coolant into the combustion chamber lifting the heads and blowing the gaskets (maybe not entirely to notice bigtime) But usually when the EGR cooler goes, especially more than once i would not hesitate to do gaskets and studs with checking the heads for flatness
3) ELC will help ALOT, maybe not a cure all thing, but flushing the system before all the work is done get that crap out of there and replace with silicate free ELC thats CAT EC-1 rater and throw a coolant filter kit from dieselsite, Dfuser, FCDp etc.
4) the remote oil cooler is not needed, the factory one is more than sufficient provided you refill with ELC and do the egr delete and coolant filter. But if you want the remote anyways than bullet proof diesel is where you want to look.
Towing usually you will see a higher delta, its cruising flat open road highway driving unloaded is when you see the 15* delta it will be an issue.
List to get you going on the road nice and safe
- EGR Delete
- rebuild Oil cooler
- replace STC fitting on HPOP
- ARP studs and Victor Reinz gaskets
- Coolant Filter
- ELC flush
- SCT with good custom tunes, (Innovative, Gearhead, Quick Tricks, Truck Source Diesel, KEM)
- Turbo back exhaust
- oil filter bypass (your injectors will thank you)
- airdogII or regulated return
- Garret Powermax turbo
Depending on your goal and bank account that will get you more into the range of power youre looking for.