There's no such thing as a silly question, particularly where shows are concerned because the chances are, someone else will have wondered the same thing (I know I did)!
Basically entry to the Novice class is determined by the date you joined the club and is only open to those that are in their first year of membership. As members aren't eligible to register Prefixes until they have been a member for a year, no one in this class is allowed to enter under a prefix name.
Members Points Class tends to be entered by regular exhibitors as the points that you score for each placing get added up and count to an annual award.
Grand Challenge is one that I recommend entering as you'll need to enter it to be eligible for Larry-Jasper to win a Certificate of Merit and three Certificates of Merit will mean that he becomes officially recognised as a champion.
Some clubs put a restriction on hire pens to give priority to the newer exhibitors. Dwarf pens occasionally come up for sale second hand so it's worth keeping your eyes out for them on the SHC Facebook Page where people will often post that they have some. At the moment, I don't think there are a great deal of new ones being made as it's only one guy doing them in his free time.