Section Business News E. Africa in Joint Promotion Drive at Investor's Seminar  Nairobi Bourse Firms Given Y2K Deadline  Kenya's Revenue Collection Surpasses Six-Month Target  Five Firms to Be Listed on Dar Stock Exchange  Arusha to Get Wireless Phone System  It's Ethics, Not Pin-Stripes, That Make a Banker - Second Opinion  Where Bill Gates Goes, There Must be Profit -Brief Case Solar Lamps, Faith for Y2K -Business Frontiers They Don't Stink, They Aren't Obnoxious, They Won't Call You `Al'-Marketing Matters