Sounds to me like you have it covered - you'll need small bills in general, not just for tipping. "I have no change" is a familiar line in Jamaica

Most people tip Lenbert $10 pp, I've tipped him more when it's been a small group.

Don't tell them your first timers because some of the higglers won't leave you alone, if they think you know the ropes, you'll have less issues

Most of all - relax and enjoy - if you were lucky enough to get Sagi at Catcha you're off to a good start!