1. As stated above, you might be OK with 87 (most are), the manufacturer recommends 89, I use 91....but then again, I do have a tuner with a 91 tune.
2. MADDOG said it best....Modding is fun!
1. I have a MagnaFlo. We could discuss how MADDOG influenced me to go this route and ultimately ended up with an awesome sounding exhaust....but I will not mention that to protect the innocent.
2. I have a Pace Edward Bedlocker. It's the 'Full Metal Jacket' with a motor and wireless remote. What can I say - "I Love IT!"
3. CAI - so many great units to choose from. I choose the Volant because I like to look of it on the 4th gen trucks. Follow the link posted above for a great thread on CAI options.
4. I have not leveled mine....yet. When I do, I will be using the Bilstein 5100 series to do it. I will also be adding additional enhancement to my rear suspension to maintain my ride height when pulling a heavy trailer.
5. As already mentioned, there are no tuning options readily available for your truck....yet.