The "change in" parameters mean the change over the past three hours. Furthermore, the change in latitude is positive (negative) if a storm moved north (south), and the change in longitude is positive (negative) if a storm moved east (west).
Current latitude and longitude are given in degrees. For latitude, always use positive values (since it is the northern hemisphere). For longitude, you will have to convert for storms in the western hemisphere, by subtracting the longitude value from 360. So if a storm is at 40W, you would input 360-40 = 320. For the upper level winds, the direction is that which the wind is blowing FROM, with 0 being north, 90 being east, 180 being south, and 270 being west. So for a wind blowing from northeast to southwest, you would input 45.