I am having difficulty with these things.

1. In the event Unit enters a distance from Unit it won't let me use a variable unit for the second unit. Any way to allow this?

2. Is there a way to keep text tags locked on the unit when it moves? I can attach it but it doesn't stick to the unit when it moves away.

3. I have an trigger that orders a unit to hold position, I have another trigger that fires when a unit is ordered to hold position. The first trigger does its job fine, but for some reason the second trigger doesn't fire. I tried putting a computer in the slot of the player that has this unit (this is all in editor testing btw), but it still won't work.

@1
Use a region and attach the region onto the unit.

@3
Does the second trigger work, if the player presses the button ingame?
You can workaround that with the run trigger action.

If I manually hold position then the second trigger works for me, but the unit i'm trying to order is for a different player.

As far as I know, no, not directly. Using a different event would probably be better, depending on what you want to accomplish.

There is an action called "Set Position of Text Tag" which takes in a point. You can periodically set it to the position of a specified unit.

There is a conditional statement to check a current unit's order. If the hold position event is supposed to fire from an order from a trigger, then simply have the trigger run when you want it to run. The event fires when a hold position has been issued by a player in-game, and not when one has been set via an action.