If a role self-visits while activating their ability, redirection will have no affect on that ability activating.
Using an item or passing an item cannot be redirected, unless specified by the role or item causing the redirect.
The target does not receive a message if they are targeted by redirection. However, intel roles can be clued in by the fact that the information they receive the following morning is not what was expected.
Sources of Redirection
Concussion can cause a visiting role to visit their target's neighbour instead of the intended target.