I'm not sure on this one. Should I stay away from the evil NPCs when playing good?

That is really a question that you have to answer yourself. If you want to play the game to experience as much of it as possible.... go ahead and take the evil NPCs. If you are trying to play them game within the contexts of a GOOD alignment (ie. you are really trying to role play the game) then probably you should avoid them. It is unlikely that a Paladin would take someone like Edwin into his/her party.
You could always play the game through concurrently with a good party and an evil party if you wanted. That would let you experience both alignments and allow you to 'role-play' more accurately. BUT if you don't have the time or don't want to then just take them anyway. Nothing bad will happen for the short time you are taking them into your party.

Hope this helps you decide!