Here are the facts. In less than 10 years, following its decision to produce its own musicals using the talent found in northern Illinois, the Paramount has acquired a subscription base of 41,000 patrons, one of the largest in the nation. This success, combined with its ongoing comedy and concert series, has allowed the theater to expand its base into a performing arts school for area residents and, beginning next season, a second subscription season of shows in a smaller theater across the street, this one devoted to plays. Other businesses have seen all the people now walking around downtown and decided to go west and join the party: recent arrivals include the restaurateur Amy Morton, who has opened Stolp Island Social, the kind of buzzy establishment more usually associated with Midtown Manhattan.