This will be the name that appears next to your comments and reviews. You can change it later via the settings button in the top right where you can also add a profile picture and amend your other account info at any time.
The crude level of any nutrient is an estimate of the total amount present in the food. The crude level does not take into account how digestible, absorbable or bio-apropriate the nutrient is so leather or hair, for example, would have a much higher crude protein level than meat even though the protein in meat is nutritionally much better.
On pet food labels, all protein, fat, fibre and ash levels are, in fact, the 'crude' percentages but many manufacturers choose to omit the word.