The smaller the wheel diameter, the easier it is to do tricks, because it makes the board sit closer to the ground. But beginners will definitely have an easier time controlling a board with larger diameter wheels. Think of the larger wheels as being akin to training wheels. If you don’t want your board to have “pop” as you are learning, you can choose softer wheels, all the way down to a 73a. They won’t let you go as fast, and you’ll have to push off more often, but they do make it more likely that your board will stay on the ground.
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.