A few questions for people seasoned in warranty law/general automotive dealership practices

Purchased a used Tundra last week and went to get it this weekend. I had noticed a few noises that were brought to the salespersons attention by me and my blind father who co-signed with me to get the vehicle. We were led to believe that they were normal on the initial test drive. Maybe the differential had never been serviced, or the exhaust exiting the side of the vehicle was the noise I was hearing, as stated by the salesperson. Maybe the supercharger the vehicle was equipped with normally made some squeaking noise. I hadn't realized the issues on the initial test drive, only after I had signed my and my fathers life away on it. I asked the salesman about the noises and he rode around in it with me and only offered me his opinions on what the possibilities could be...he never offered to have a technician look at the truck for me and I was assured that I had purchased a warranty, anything that would pop up would be covered by it.
I got the vehicle from the dealer "cold" Thursday night and it sounded horrible (after I have signed papers, after I have drove a total of 12 combined hours to get this pretty white truck). Every time the vehicle would downshift I would hear a lot of chatter from what I believed to be the differential, and the belt squeak (that I had pointed out to the salesman, whom also said it was probably normal because the vehicle had a dealer-installed supercharger kit on it) was very apparent on a cold start. I had a four hour drive home so I decided to "service" the differential before I drove home (essentially drain and refill) to hopefully ensure my, and others safety. I drained the fluid to find many, many metallic shavings and hunks in the fluid. I filled it with conventional gear oil and a MOC additive purchased from Toyota and the differential still made the same noise.
I decided to drive the vehicle home anyway as I was pressed for time to get the person helping me drive it back to southeast Texas. Sending this truck back to the dealership that obviously did not want to own up to fixing it properly(and that could not identify the four major issued on the vehicle prior to selling it, two of which are serious safety concerns) was absolutely not an option.
Around 80-100 miles into the trip the check engine light came on. A few minutes later my girlfriend called me to tell me that I had a brake light out. A brake light? I can not even get the vehicle inspected, and it likely needs thousands of dollars of service. I drove the truck straight to my local Toyota dealership and there it sits, as I pay insurance and my $450 truck note. I am expecting these things to be fixed, and also purchased a factory warranty (which I feel should not need to be used in this instance). I have been relieved of my position as an automobile technician over much less than this (not realizing that a tire had a bubble in it), and feel the issues with this truck show severe negligence from the service department as well as the sales department. I brought the issues up before the vehicle was delivered to me and was offered no option aside from that they were "normal".

The truck has a modified suspension (including a lowering kit and tractions bars on the rear), and a TRD supercharger bolted to the engine. I am 100% sure that the combination of these things is what caused the differential to fail, and I am also sure that Toyota will agree. I do not need any of these things as I will not be drag racing the vehicle, I bought the truck because it was a regular cab, had low miles, and the supercharger (rumored to help a little in the MPG area). I purchased this vehicle from a TOYOTA DEALERSHIP with all of these modifications installed. I also purchased a 3 year, 36,000 mile warranty with these modifications also installed through Toyota from the same dealership. I am assuming that that would mean that this vehicle can be warrantied with these modifications on it. Is this correct or not?

Just looking for anyone with experience dealing with this. I have already contacted Toyota and the BBB about the issue. Thanks in advance.