I had been a little confused over the difference between the National Park and National Forest.
Will there be massive sequoias there I can photograph and just look at in awe?
The US land management system can be dauntingly complex for tourists. National Forests (and Bureau of Land Management areas) contain vast tracts of land with all sorts of different primary uses, with scenic or recreational attractions usually being a bit lower-profile than NPs (not always true, but generally). National Parks are lands set aside specificially for their scenic, recreational, scientific or culutural significance, ususally with much more developed visitor services. Most foriegn visitors have only heard of the NPs, and if they have heard of other natural attractions outside the NPs, they often understandably assume that its all part of a NP. Sequia NP and Sequoia NF are a particularly confusing example. Another good example is Horseshoe Bend - it is sort of near the Grand Canyon and is often featured with the GC in marketing materials, but it is not part of GC National Park, and the canyon is not the grand canyon.
Anyway, FWIW, you can see the giant trees in Yosemite, without a time-consuming detour to Sequoia (and sparing you an essentially wasted night in Bakersfield).
Although I see what you're thinking with Day 6, I'm going to side with the others that it is a pretty nutty schedule. Don't do this to yourself. Its technically possible, I suppose, but like has been pointed out above, leaves absolutely zero margin for either things going wrong, or slowing down to enjoy yourself a bit more. "seeing more" doesn't necessarily mean ticking off more boxes, it might mean doing a bit better job seeing the places you are most interested in. I'd start by not trying to squeeze in an hour at GC North Rim. If you're going to go to the north rim, it demands at least a full half day, and more is better. Otherwise, skip it and make better use of your time at the South Rim.
I do hear what you're saying about scheduling a bit of a margin for yourself at Vegas, since you can't miss the concert. But I do think you've gone a bit far in that regard, having multiple days of hiking at Red Rock and a couple more just kncoking around Vegas, and just a couple hours each at Zion and Grand Canyon. That's all out of whack. Also consider that September is still more or less summer in the desert around Vegas - you'll enjoy hiking a lot more at other spots on your itinerary.
Other comments...the Zion shuttle is not a "tour", its just a shuttle bus that goes up the canyon and back down. A single shuttle bus ride a Zion is a tragic waste of a visit, compounded by the fact that you'll likely be driving out of the spectacular east entrance in the dark.
FWIW, #3 misses the point a bit with driving at night. I'm a "local" and I don't avoid driving at night, nor does anyone else I know. I've driven these very roads at night literally thousands of times. You do have to be extra vigilent for animals, that much is true, but I would not build my trip around that concern. More significant to me is that you can miss a lot incredible scenery driving at night - the whole reason you're here.
Anyway, IMHO you should look over each of these comments carefully and construct a new, slightly looser itinerary that doesn't try to do quite so much so quickly with such tight tolerances.