Grabber yellow is a like or don’t like color, and some may think that is a bad thing (GY is the main reason why I bought my GT500). I would say right now is not really a sellers market unless you under value your car; expecting a dealership to give you a ”good” deal is over as they also see...
With those miles I would not worry too much. I bought my 500 used with 12500 miles and any issues I have had been covered under warranty (wheel bearing, axle shaft leak, steering wheel wear).
I run Nittos, mainly because they can be rotated side to side to help with tire wear. They are fine on the street as long as you warm the tires up before pushing the car.
I own a turbo 4 mustang and a s/c Shelby, both are fun to drive and both have their down falls. Buy what puts a smile on your face, the rest does not really matter.
Yes the base wheels will fit and LMR sells and open style lug nut to work with the CFTP wheel studs.
https://lmr.com/item/WCW-W1014BK/mustang-acorn-style-lug-nut-kit-14mm-open-end-1516
It have the 7000 series and use it on just about everything from my cars, jeep, truck, and motorcycle. It hangs on the wall when not in use, and a highly recommend the caster mod.
I use these on my Shelby when I need to trailer it, they work great and I do not have the crawl under the car.
https://www.macscustomtiedowns.com/straps/automotive/packs/6-foot-direct-hook/p/512656/
Stay away from a Ford battery (they do not last long).
Here are a couple options.
https://www.odysseybattery.com/products/odp-agm96r-battery-96r-600/
https://4xspower.com/bci_group/96R/