Hello Itsinmyeyes, hope your PCT plans are still go. smile
There's been some good answers to your questions.
As far as your comment about being told that you can't do it and refusing to believe that, then your belief has already got you a good way along the trail! As someone else mentioned, a great deal of a successful long distance hike is mental attitude. If you really want to accomplish it, then barring accident or injury, you will. It is after all, only a series of day hikes. If you stick to it, your fitness whatever it is at the start, will only improve.
Re' footwear, as has also been said, that is a personal preference. Personally I prefer a leather boot (Asolo) and find them neither too heavy nor too hot. They also give good support, especially if carrying a full pack. I've tried 'shoes' but badly sprained an ankle once in a nanosecond of inattention. If that had happened on the PCT it would have been disasterous. I find boots will take me across rivers, through snow and can even accept crampons if required and still last the distance, so for me they are a preference. But that's just my opinion. If you hike better with shoes or runners then go for it, but be aware that there will be less support.
Six months is plenty. I took five (calendar) months on that particular hike, and I averaged 17 miles per day over that period. (That included 'layover' days) Keeping up a steady mileage is important. You'll only have a certain 'window' to do it in because of seasonal changes. Take too long, and you run the risk of getting 'snowed out' before you reach the Canadian border.
I guess the two main pieces of equipment for a successful hike, if you have to pick just two, are your footwear and your pack. Don't skimp on those. In fact get the best you can afford of all your equipment. e.g., my pack and tent are now 19yrs old and still doing the biz. They were not cheap at the time I bought them and they've paid off with many miles of use.
Good luck, it'll be a grand experience, it'll change you in subtle ways, and it'll be an experience that will stick with you as long as your memory does!



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Dances With Marmots