Your exhaust is now breathing easily, doing the other side (filter) just makes sense. The DIY is a good, cheap, alternative. Just stay away from the foam/gauze & oil (like the K&N). My preference is the Ford AIS, more expensive, but it looks "right"...
As for the tuning, no one has that answer for you, just what they
chose. It's like asking what the Best "oil, tire, battery, etc is"
Usually, the three steps are;
Breath better (filter & exhaust)
I would advise against trying to short-cut the last two with one of those "All-In-One" apps that give you "fake" gauges (digital LCD) and "hokey" tunes. Do it right, get the real thing from the start.
In no particular order;
DPTuner (unless you have, or plan to have, HID headlights)
Boost isn't everything, with a free-flowing motor you'll see 20psi or so, tuning gets more, maybe 30psi or more (look in the Performance Forum for a topic about a new wheel that exceeds that)
Read, Read, Read, there's a lot of variables depending what you plan to do in the future and what you use your truck for!