Is Detect Evil sight based? Can Detect Evil be used by a blind character in combat as an IC justification for clicking on the evil things around him and beating them up? If I am blind, and there are pelluscent things around me, does that mean that I have heard them and can start swinging at them? What about spells like True Seeing/See Invis/Ultravision? Do they work on me?

Am I immune to gaze attacks? Does that make me immune to all the nastyness Beholders can do?

You may hotkey detect evil and, if successfully used in combat (passing the concentration check), have an IC rough sense of where the evil is.

It is reasonable to attack back at things right next to you that are swinging at you.

True Seeing/See Invis/Ultravision have no effect.

You are not immune to gaze attacks, nor immune to beholder rays (it's more like they're shooting magic beams at you rather than anything else).