My tub and sink faucet drip when I flush my toilet. Also have sewer smell in the house and have heard a gurgle from the tub when flushing... not always though. Drain in the sink is slow... using Draino as we speak... but the problem has been around longer than the slow drain. Does this sound like a blocked vent?

Drip and smell are unrelated, what is your water pressure coming into the house? Smell, gurgle do point toward a vent problem so stop with the draino and rod from the roof with enough snake to reach roof to basement floor plus 20'

I'm having the same issue with regards to the drip. I've recently added another bathroom and as soon as the plummer laid the pipes for the addition, my existing bathrooms drip whenever I flush a toilet or run a bath. This clearly has to do with a pressure gradient. Haven't fixed it yet... Regarding sewer smell: it's very possible that your tub or washing machine drain doesn't have a J or P trap. I washing machine was missing one so whenever we ran a wash the whole house reeked like a dead animal. Once I installed a trap in the washer drain the other went away.