new member with questions.................help

i drive a 09 4 cyl taco...........after reading several threads in this forum i have the following questions.... 1. what is the "second charcoal filter" and where is it. does removing it result in power or performance gains can u damage anything by removing it. 2. is there anything you can buy at auto parts store or online for underbody frame anti corosion diy type. 3. can 31x10.5 tires be safely run on my stock 15x6 stock wheels. if not what kind of affects can it have . can the tires flyoff at highway speed will they wear uneven ? i had them mounted on my stock 15x6 wheels for two weeks with no incident till i picked up 4 new 15x7s. all was well till i get home and turn up da driveway and the tires rub against this blockish piece of plastic protruding from the 2 oclock position (drivers side) of the fenderwell. i pull back on the plastic liner and theres a box looking plastic with bolts . this on both driver and passenger fenderwells. 4. what is this and can it be removed or smashed to make room for the tire. thanks Ahead of time for your input tacomasters....