An E85 conversion won't affect the reliability; the urge to turn up the boost to fully utilize the properties of E85 will lol. And that is the age old question, to buy a modified car or to buy a stockish one and modify it yourself. In retrospect, I could have saved between 10-13K if I had purchased this car already fiddled with but the downside is I wouldn't know inside and out the issues as they arrise.
Routine maintenance that will get you every time.
Engine Oil
Brakes. If you want to go fast, you need to stop. Make sure everything is up to spec. A lot of owners don't flush the brake system as often as they should (myself included...on the list).
Belts. You have three, Timing / Balance / Accessory. Good thing to know is all the parts are Gates manufactured, which can be Amazon primed. If you're balance shaft belt goes, it can take out the timing belt. If the accessory belt goes, there goes your water pump. If the timing belt goes, built motor time!
Basic Modifications
And thats where I stop on the recommendation limits, I haven't found a part on the car I couldn't change out, with the only major items left for me being the transmission, transfer case, and drive shaft. The EvoM forums are chock full of modding for beginners, and I don't want to necessarily beat the horse. The "Official" Evo Modding for Dummies