Torque news is as accurate as Jalopnik which are basically automotive tabloids.
For 2020, the Pro 4Runner got Carplay compatibility, a new color and push button start. That's all and figure the Tacoma will get minimal updates as well.
Average. Intake and exhaust systems aren't all too restrictive now in most vehicles especially non performance vehicles. Forced induction will add the most but the TRD/Magnuson kit is non intercooler. There are some modded kits out there that add one though.
Been saying for years but people think higher grade on an engine tuned for a low grade means more power. If anything a higher grade means less ethanol but some states such as CA have the same ethanol content on all grades.
In your situation, save, save, save. A good lift is expensive. Don't look at Junk Country, Revtek or any other kind of spacer lift. Being a 2008, I'd make damn sure the maintenance is up to date.
You're just trying to replace the headunit? Crutchfield carries everything you need. There is a JBL interface you will need if you intend to keep amp that powers all the speakers in the truck. I suggest the iDatalink kit for plug and play install.