Congrats on your purchase. I think there are a couple of things to answer before these answers will really help you but we'll all try. Some of those questions are:
1) What are your actual goals for the car (speed, hp, track car, stance, etc)
2) What car are you coming from? Speed is subjective to most people. If I drove a 98 Corolla everyday, the second I get in a base model Sonata, I might think that's "fast"
3) The last sentence you wrote is confusing as all hell. How do you keep a car stock and "unlock potential"?
Anyway, I'll give my 2 cents on the numbered questions.
1. 1.4 is the fast. Get that, nobody says you have to use all the boost that you get with it. It also doesn't matter your octane, Lozic will tune for 91. and you can have 1.4 or probably 10.8 idk. They are separate items.
2. Yeah, I think I'm shortening the life of the transmission with this pressure. But Hyundai/Kia/Genesis do not have a troubled past with transmissions, so I'm just not that worried about it. If I were to do it again, I would probably choose 0 because I like smooth shifts. I do not regret my decision, and the upside is that car is faster. I race, it helps.
3. Just take all the power and learn how to control your foot. The car feels very different in Eco mode vs Sport, but it never feels slow.
4. AWD isn't worth it for you without goals listed. Specifically, if you're not road/racing, time attack, autocross, or whatever else goes in there you probably won't notice the difference. I have it, I think it's worth an extra .1 to .2 in the quarter mile and I had the money. I don't suggest it for most people unless they have the rest of their
mods list complete.
5. Buy a JB4 because there are a lot of things you can do with it, including checking logs.