As far as the bed cover goes, I made by own with some leftover exterior plywood I found thrown out at a construction site and some glossy exterior white paint. Cost about $15 and looks pretty good if I do say so myself. Don't think I posted any pics of that, but I can.
As far as the grille blocks go, darcane is probably the guy to follow since his truck is the same as yours. For other ideas you can check out what I did here:
http://ecomodder.com/forum/showthrea...wer-19810.html
As far as synthetic go, they'll probably do some, but they're not going to make a huge difference. When you figure whether or not it'll save you money keep in mind that synthetic oil generally gives longer oil change intervals. I use synthetic in my wife's Blazer because I change it myself and that way I don't have to change it as often. Don't forget that you can also synthetic gear oil in your axle. One of the advantages of synthetics is superior low temperature performance, so they help warm ups and cold weather performance. Ganted, like I said earlier, they're not going to buy you a ton. I definitely wouldn't go out and change to synthetic unless you're already due for a change.
As far as how high tire pressures help, the higher the tire pressure, the less the rubber flexes and absorbs energy when rolling. You can imaging if you had a solid steel wheel vs a wheel of foam rubber--the steel wheel rolls a lot easier. Same concept.
You might want to look into getting a block heater and/or an oil pan heater too. Helps with cold weather startups.