I have not given this much thought just now, but I was able to discuss this topic with some linguistically-aware native speakers the other day. What I remember learning was that the tonal workings on the V-tio̍h ADV structure are not what You would expect. It's actually liàntiāu（～「変」調） on the verb, and khiātiāu（～「本」調） on «tio̍h». Weird, huh. Apparently, this is the rule all over TW.
Your descriptions seem to be spot on.
I'd use «chiòⁿ liáu» over «chiòⁿ tio̍h».
I've never really mastered the «tio̍h». I only use it when nothing else seems to fit. I need to work on it.
Something that suddenly came to mind is whether ergativity's got anything to do with it. Is «tio̍h» kind of like this ergative «liáu»?
One thing that's on my mind also is the «zero complement». I think sometimes just the bare verb is enough. Exactly when this is true, I've yet to figure out. I think I've been over-using the zero complement. It has something to do with non-native speaker hearing. You think the native speaker used no complement, but actually it was there in a clipped form.
I have a bit much on my mind right now, but I think it's great that we're talking grammar. This is much needed in the Hoklosphere, in the face of an unspoken belief that grammar -- at least for "Chinese" languages -- is a non-factor.