Does beta blocker nebivolol (bystolic) lower heart rate at the lowest dose 2.5mg, if so by how much. if you stay at the lowest dose do you still need to taper down when discontinuing the drug (by cutting the pill)?

It should still have the bradycardic effect at the lowest dose but estimating how much is not easy because it varies individually. Yes, you can taper to one every two days for 4 days then one every three days for 6 days then stop if you really want to be safe. However, I would say most people can stop immediately at the lowest dose of 2.5 mg without significant rebound effect by my experience.