New Thornmail vs Old Thornmail

I don't really understand how Thornmail works. It reflects Basic Attack damage, by a percentage before armor is taken into account, but do additional effects on a basic attack become reflected as well?

For example, a Vayne deals a bit of her damage through botrk, which isn't technically basic attack damage, so it isn't reflected. Would the same go with her Tumble, that grants bonus damage equal to 50% of her bonus attack damage? It is called bonus damage, so is it considered the same as the basic attack and will be reflected?

Same goes for other champions like Kalista, who relies on gaining a bunch of stacks on you with her second or third passive (You know how those new champions are. :P), then using Rend. Since she doesn't hit very hard before using Rend, wouldn't the armor% damage bonus be better than just damage returned?

Would a Nasus who hits a target with his Q have his stacks or Trinity Force damage reflected?

If these bonus damage abilities aren't reflected, wouldn't the new Thornmail be better than the old one with a lot of armor stacked?