Well Nos on any engine isn't good if u're not using it rite and did upgrade the fuel. Upgraded fuel rail and pump is pretty safe to run NOS. Yes theres a button and i'd say u turn it on on 3rd gear cause if u miss gear ..kiss ur engine good bye. To be safe leave it on for like 8 seconds
Turbo i guess its easier to have. Upgrade ur fuel and tune it up just rite so u can drive it daily