First time holiday/road trip in the USA

Me and my best mate are travelling to the USA for the first time for each of us this October for a couple weeks, we are renting a car which I am driving the whole time for 1500miles give or take, our trip is as follows:

•LAX for a night then driving out to a festival in Indio

•Drive up to vegas for a couple nights in a hotel next to Fremont st

•Drive across to the Grand Canyon for a canyon tour and 1 night in a hotel

•Drive back to LA, return the car and have booked a hotel for 4 nights in Hollywood

Now what I’m asking is any perspective on things I should do or watch out for while out there, I have gathered tipping is a big thing over there, is that for everything like food and taxis? Tour guides?

Anything we should be careful of in any of those destinations?

Any driving tips or things to keep in mind? I am a an experienced driver but will be my first time in another country and have heard LA is one big traffic jam most of the time? What I’ve got from my research on that is to always turn on red unless otherwise stated and expect people to undercut me anywhere?

We are renting a dodge challenger should I be concerned about it being broken into or am I overthinking that? I will be taking out 3rd party hire car insurance that seems to cover everything

We both have our ESTA’s but my friend says we need an i94 (I believe it is) but I can’t find anything concrete through my searching, if anyone could confirm?

Thanks for any input or advice, I am super excited to be exploring and seeing a small part of the USA!:)