Is it viable to do chaos runs Edith a fohdin at beginning og ladder with crap gear like Dual spirit and lore etc and merc with insight?

yes and you don't even need the insight if you run redemption.

Make sure to buy a teleport staff to get past maggots then go to town.

Where do i buy a teleport staff? And should i run him AS a zealer thrrough normal ? Them hammer om nightmare and Then foh on hell or?

easiest is running holy fire through normal. Then you can kind of pick to go either one really.

To get a teleport staff early when you are level 19-23 go shop ormus (act 3) look at the staff that are out of your level range (will be red) the teleport staff is level 24 so it makes it easy to shop. If you are level 24 or higher then just look at all the staffs until you find a teleport charge staff.

Hammer will be better damage but foh is safer playstyle

for Foh you will have issues with animals but if you have an okay merc you shouldn't have an issue. Foh has lightning damage so you can kill stuff. When you get to hell you need conviction to help deal damage to animals or just a teleport staff to skip through it.

I shop the staff in normal or nightmare ?

any but if you 19 you probably be in normal