You can shift the auto trans like a manual if you'd like. As Scott posted, the "power" button just delays upshifts and promps earlier downshifts. In a perfect world, the up/down shift delay/prompt would be programmable, but we just have to put up with seemingly premature downshifting with "power" engaged.

4-low splits the power 50/50 and should NOT be used on pavement (unless snow/ice). Gear reduction is 2.48:1. When shifting into and out of 4-low you must be at complete stop and in neutral.

Many of us use synthetics, I use Mobil 1 5W-30.

No cargo liner is commercially available, but like you I have a big dog. My wife made a cool tailored liner out of red denim, then I installed snaps. It looks sharp, and protects the carpet from whatever my 100lb lab drags in, which is usually mud, water and stink!

If you get the supercharger, it will feel a whole lot more like your Mustang.

Welcome aboard, Tom!