Here's some general guidelines to get you started: Narrower decks are lighter and easier to flip, but you’ll sacrifice some stability. Wider boards are more stable but are heavier and slightly less ideal for some tricks. Skaters who like flip tricks, manuals, ledges, and flat bars usually prefer boards on the narrower side of the spectrum (7.75 – 8.25 inches). Those who skate big bowls, hand rails, or like to jump down large gaps at high speeds are usually more comfortable with a larger board (8.25 – 9.0 inches).
Krux make some great trucks. Krux makes "downlows" trucks, that have a lower hanger and kingpin than even Grind King. However, you will need a hex tool to adjust them. The Krux IIIs with Topless System are even lighter, with special bushings that feel broken in from the start, but that also provide a faster snap back into position. Krux trucks are light and low.

Without good grip tape, skaters have a tough time staying on top of their board. The main complaints about poor grip tape tend to be that it was never very grippy or lost its grip really quickly. Once again, we recommend trusting in name brands with years of experience supporting skateboarders. Unfortunately, if you are buying a pre-made complete skateboard, you probably won't have access to the brand name of the grip.