The AE was about $360 when I bought it. No idea what they want now. It has saved me at least 10 times that in parts and service expense and has made me pretty popular with the folks around here who have powerstrokes. I've seen some stuff on Torque Pro and thought I might get it. But I don't have an Android phone
I'm reluctant to begin using HotShot or other additives because from what I've heard, once you start, you have to keep on with it until you get new injectors. If I start having run-time problems with stiction, I'll probably try some while waiting for a set of injectors.
I thought about the AIS but haven't had any problems with the stock airbox. And it's not real dusty around here, anywayI always use Motorcraft filters (fuel, oil, air). The oil filters for the 7.3 at walmart are only $10. No discernable blowby using the oil filler cap test. On the 6.0, a previous owner had put on a Banks airbox and filter. From what I've read about the 6.0, the stock filter outperforms all the aftermarket stuff until you go to big HP mods. So I traded my Banks for a stock airbox and stuck in a brand new filter. I priced a new oem box. It was around $500 if I recall. The filter itself was pretty expensive, but it seems to last forever.
I put coolant bypass filters on both PSDs. Not sure the 7.3 needs one, but it's cheap insurance. The 6.0 definitely needs one 'cause the oil cooler passages are so small. I also changed out the turbo pedestal on the 7.3 to get rid of the leaking EBP servo. Other than that, no mods. I did have an oil leak at the pan where the dipstick enters. It was not just a drip, either. So I got one of those billet dohickeys that replace the oem dipstick/pan interface and put it in. It works well but I think they got me for about $300. Still cheaper than pulling the engine or cutting the crossmember when you consider downtime as part of the expense. My 6.0 just has an egr delete installed by a previous owner. On trips I monitor the oil temp versus coolant temp since it's possible to have a catastrophic overheating situation with no warning from the stock instruments. I've toyed with the notion of just putting gauges in to monitor those items, but I'd rather work on my bikes.
I did a fair amount of research before I got my 6.0 and decided it would have to be an '06 or '07 for the reasons you mentioned. It was a high mileage truck, but that doesn't bother me much with a diesel. The FTE forum has been a great place for me to learn. As far as youtube goes, the only guy I've found who is straight up and very helpful is dieseltechron. Unfortunately he was killed in an accident a year or two back. I don't know if anyone has stepped up to fill his shoes.