A couple quick questions...

1) I know that you can give units hidden passive abilities using a disabled spell book, but using that same method can you give that unit a hidden active ability then order that unit to cast said ability?

2) GUI has 2 actions for creating special effects, one is at a location and the other is attached to a unit. The one attached to a unit still leaks a location, am I right?

1) I believe so

2) No, it attaches directly to the unit so no location is used.

Thank you kind sir, I'd give you some rep but the system won't let me. You've been helping me too much lately :(

edit: ahh I can't convince it to order the unit to cast spells within the spellbook through triggers. I could technically do it by forcing UI keys but that doesn't work with it being disabled.

This won't work. Disabled spell books only work with auras or passive abilities such critical strike or evasion. If you add an active ability, it won't work.
For more information on spell books you could check my map, since I use them as buffs for my units.

FP, can't you just use tornado slow aura or something ?

No, because that way I would be forced to have a tornado following my affected units to all places on the map (which would be stupid, but lol xD ).

Unless of course, I make no idea what you are talking about, my above rule still applies.

I tried this once, I used a disabled spellbook with defend, it did work though, maybe spells that are targeted doesn't work, I'll try testing it too.

Just curiosity, are you guys saying that, per example, if I have 2 slow spells, both with tornado slow aura, they will stack?

It gives a buff, and you can set it to have no targets, so you only need it instead of a spellbook + another ability to have custom buffs

Defend works inside a disabled spellbook, I tried using Divine Shield and it didn't work.

Looks like abilities that have unlimited time work ... while timed abilities don't. You should keep in mind, defend is quite passive too.