Right on then!Not really, no. Which, excluding the cost saving, was the main reason I wanted a used 18+. There's a pretty low probability of just an E85 tune grenading the motor and/or transmission but if that happens rebuilding or swapping either of those for a used one can be done not easily but doable for me. The only issue I would have is the diminished value of the car when resale time comes but it's a risk I'm ok with
Mod away. In fact, do everything you've listed, all of it. They're all good mods that will take you where you want your car to be. It's clear you've thought things through properly, and you've gathered good knowledge on what you want to do.
Most people aren't as together in their ideas.