It would be really nice if I could tell my autocaster to fire in the direction of a particular block I set, say to use the plan focus medium for various tasks: plan fire for a firey death trap, plan rift for sick af doors, plan break for making my autocasters do breaking work instead of golems, and so on. Targetting a block might need to be restricted to a redstone signal only to avoid draining the aura.

How? We already have the Golemancer's Bell, though Thaumic Additions chose to create a new tool for its sentient chest item. Also, you already have a new tool, though the Impetus Resonator comes later in research than the autocaster. I'm not entirely sure what the best choice here would be.

One sticking point came to mind: ward focus effect. Who should own the ward, the autocaster or the Thaumaturge who placed the autocaster? If the autocaster owns it, what should happen to wards it created when the autocaster dies or is picked up?

I've seen that you have mechanisms to make wards owned by a Thaumcraft Boss disappear when the boss dies. That's actually really cool and the same solution could be used here to make the autocaster own its own wards. But I'm certainly not opposed to the idea of the Thaumaturge who places the autocaster owning the wards.

Having a way to arbitrarily cast spells at spots in the world isn't a bad idea, and while I did wonder if it would be a little overpowered the same could probably be said for the mob-targeting autocaster. However, I'm not sure if giving this functionality to the autocaster itself would be the best idea, since wrangling mobs to make them perform consistent tasks (like doing something in a set spot over and over again) can be a rather painful thing to figure out in modded Minecraft, so if it were to be implemented it would have to be thought out well so that it wouldn't be overly frustrating to use. However, I do have to follow this up with my usual warning that development has been very slow lately, so if something like this were to be added it wouldn't be done any time soon I'm afraid. It can, at least, be kept in mind for the future.

Also, regarding spells like ward plus autocasting, honestly we didn't really discuss the matter much about how that would work, but it would make probably be best to have an autocasted ward be owned by the person who created the autocaster. I'm not sure if this is already how it works, but nonetheless that makes the most sense to me.

No idea about actually adding this, given how many bugs and such I have to track down, but at the moment wards casted by autocasters do indeed make the wards owned by their owners, so nothing unexpected should happen there. In the event anyone actually is crazy enough wants to add a similar thing with compat for another addon or something, the ward focus checks for the IWardOwnerProvider capability on the casting entity.