Yes, there is a Tour Desk in the CTI lobby that can help you with any tour, from any tour company. Chukka Caribbean Tours is the most popular for the zip line. We did it from CTI in 2007 and had a blast. At that time, there were two tour options - a morning and afternoon. It's about 4 hours.
For parasailing, you'd have to actually go in to Ocho Rios for this as there aren't any vendors in the CTI bay that provide this.